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It has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep ...
Answer
#7: Post edited
by
Lundin
·
2023-08-22T10:04:44Z (over 1 year ago)
- It has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero, well-defined and portable.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type. It can only wrap-around.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
- It has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero, well-defined and portable.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type. It can only wrap-around.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> - 1 bytes, likely 2<sup>32</sup>-1 or 2<sup>64</sup>-1 on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
#6: Post edited
by
Lundin
·
2023-08-22T08:34:04Z (over 1 year ago)
- It has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero, well-defined and portable.
- Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type.- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
- It has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero, well-defined and portable.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type. It can only wrap-around.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
#5: Post edited
by
Lundin
·
2023-08-22T08:33:24Z (over 1 year ago)
- It has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- That `man` page is confused and has some technical problems:
- It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero.- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
- It has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero, well-defined and portable.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
#4: Post edited
by
Lundin
·
2023-08-22T08:31:28Z (over 1 year ago)
It a has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
- It has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
#3: Post edited
by
Lundin
·
2023-08-22T08:26:19Z (over 1 year ago)
- It a has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
- It a has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
#2: Post edited
by
Lundin
·
2023-08-22T08:23:53Z (over 1 year ago)
- It a has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
- It a has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed.
- The C99 rationale document points out that `calloc(0, sizeof(OBJ));` is apparently wide-spread use (according to the rationale), supposedly as a way to distinguish between "nothing allocated" and "zero bytes allocated". The Committee did not recommend it - this is implementation-defined and non-portable (and soon to be explicitly undefined behavior in C23).
- I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented).
- That `man` page is confused and has some technical problems:
- - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero.
- - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type.
- In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place.
- - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API.
- - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.
#1: Initial revision
by
Lundin
·
2023-08-22T08:18:53Z (over 1 year ago)
It a has 2 parameters for weird historical reasons that nobody seems to know the rationale for any longer. Like most functions in the C standard library, the function API was not well-designed. Keep in mind that many of these functions were designed in the 1960s(!) and early 1970s, some 20 years before good programming practices were invented. By the time C got ISO standardized, they chose to pick existing functions at a whim rather than encouraging better functions to be designed. I just checked K&R 1st edition and it has two functions `alloc` and `calloc`, with a corresponding `cfree` for `calloc` specifically. `calloc` has 2 parameters even there and K&R 1st edition recommends a cast of the result (I believe `void*` had not yet been invented). That `man` page is confused and has some technical problems: - It is not possible for the unsigned `size_t` argument of `malloc`/`calloc` to _overflow_, although _wrap-around_ is possible. These two terms have very different meaning in C. Overflow means signed overflow, which is undefined behavior. Wrap-around means an unsigned integer going beyond the max value and starting over at zero. - Similarly due to "the usual arithemtic promotions", `nmemb * size` cannot overflow, given that at least one parameter is `size_t` or another large unsigned type. In case neither operand is a large unsigned integer type, then that's a caller-side arithmetic bug completely unrelated to the `malloc` function. Like for example the common beginner mistake of typing `int` all over the place. - `malloc` can at most allocate 2<sup>(CHAR_BIT * sizeof(size_t))</sup> bytes, likely 2<sup>32</sup> or 2<sup>64</sup> on mainstream systems. `calloc` opens up the possibility to request even more than that through its dysfunctional 2-parameter API. - So the only "increased" error checking `calloc` can do internally is to ensure that no over-allocation caused by `calloc`'s own bad API is taking place.