doc: add missing ctype.h, sys/stat.h, stdlib.h descriptions

JIRA: CI-269

libc/functions/README.md

@@ -1,6 +1,6 @@
 # Functions
 
-## _
+## \_
 
 [`_exit`](./_/_Exit.part-impl.md) <!-- #updated# -->
 [`_Exit`](./_/_Exit.part-impl.md) <!-- #updated# -->
@@ -99,13 +99,15 @@ endthread,
 [`fputc`](./f/fputc.part-impl.md), <!-- updated -->
 [`fputs`](./f/fputs.part-impl.md), <!-- updated -->
 [`fread`](./f/fread.part-impl.md), <!-- updated -->
+[`free`](./f/free.part-impl.md), <!-- updated -->
 [`freeaddrinfo`](./g/getaddrinfo.part-impl.md), <!-- updated -->
 [`freopen`](./f/freopen.part-impl.md), <!-- updated -->
 [`frexp`](./f/frexp.part-impl.md), <!-- updated -->
 [`frexpf`](./f/frexp.part-impl.md), <!-- updated -->
 [`fscanf`](./f/fscanf.part-impl.md), <!-- updated -->
 [`fseek`](./f/fseek.part-impl.md), <!-- updated -->
 [`fseeko`](./f/fseek.part-impl.md), <!-- updated -->
+[`fstat`](./f/fstat.part-impl.md), <!-- updated -->
 [`fstatat`](./s/stat.part-impl.md), <!-- updated -->
 [`fsync`](./f/fsync.not-impl.md), <!-- updated -->
 [`ftell`](./f/ftell.part-impl.md), <!-- updated -->
@@ -146,8 +148,20 @@ gettime,
 ## i
 
 interrupt,
+[`isalnum`](./i/isalnum.part-impl.md), <!-- updated -->
+[`isalpha`](./i/isalpha.part-impl.md), <!-- updated -->
 [`isatty`](./i/isatty.part-impl.md), <!-- updated -->
 [`ioctl`](./i/ioctl.part-impl.md), <!-- updated -->
+[`isblank`](./i/isblank.part-impl.md), <!-- updated -->
+[`iscntrl`](./i/iscntrl.part-impl.md), <!-- updated -->
+[`isdigit`](./i/isdigit.part-impl.md), <!-- updated -->
+[`isgraph`](./i/isgraph.part-impl.md), <!-- updated -->
+[`islower`](./i/islower.part-impl.md), <!-- updated -->
+[`isprint`](./i/isprint.part-impl.md), <!-- updated -->
+[`ispunct`](./i/ispunct.part-impl.md), <!-- updated -->
+[`isspace`](./i/isspace.part-impl.md), <!-- updated -->
+[`isupper`](./i/isupper.part-impl.md), <!-- updated -->
+[`isxdigit`](./i/isxdigit.part-impl.md), <!-- updated -->
 
 ## k
 
@@ -285,13 +299,16 @@ resourceDestroy,
 [`strcoll`](./s/strcoll.part-impl.md), <!-- updated -->
 [`strcpy`](./s/strcpy.part-impl.md), <!-- updated -->
 [`strcspn`](./s/strcspn.part-impl.md), <!-- updated -->
+[`strdup`](./s/strdup.part-impl.md), <!-- updated -->
+[`strerror`](./s/strerror.part-impl.md), <!-- updated -->
 [`strlen`](./s/strlen.part-impl.md), <!-- updated -->
 [`strncat`](./s/strncat.part-impl.md), <!-- updated -->
 [`strncmp`](./s/strncmp.part-impl.md), <!-- updated -->
 [`strncmp`](./s/strncmp.part-impl.md), <!-- updated -->
 [`strncpy`](./s/strncpy.part-impl.md), <!-- updated -->
 [`strpbrk`](./s/strpbrk.part-impl.md), <!-- updated -->
 [`strrchr`](./s/strrchr.part-impl.md), <!-- updated -->
+[`strsignal`](./s/strsignal.part-impl.md), <!-- updated -->
 [`strspn`](./s/strspn.part-impl.md), <!-- updated -->
 [`strstr`](./s/strstr.part-impl.md), <!-- updated -->
 [`strtod`](./s/strtod.part-impl.md), <!-- updated -->
@@ -325,6 +342,8 @@ timeGet,
 timeSet,
 [`tmpfile`](./t/tmpfile.part-impl.md), <!-- #updated# -->
 [`tmpnam`](./t/tmpnam.part-impl.md), <!-- #updated# -->
+[`tolower`](./t/tolower.part-impl.md), <!-- #updated# -->
+[`toupper`](./t/toupper.part-impl.md), <!-- #updated# -->
 [`truncate`](./t/truncate.part-impl.md), <!-- updated -->
 [`ttyname`](./t/ttyname.not-impl.md), <!-- updated -->
 [`ttyname_r`](./t/ttyname.not-impl.md), <!-- updated -->

libc/functions/f/free.part-impl.md

@@ -0,0 +1,36 @@
+# Synopsis
+
+`#include <stdlib.h>`
+
+`void free(void *ptr);`
+
+## Description
+
+The `free()` function shall cause the space pointed to by _ptr_ to be deallocated; that is, made available for further
+allocation.
+If _ptr_ is a null pointer, no action shall occur. Otherwise, if the argument does not match a pointer earlier returned
+by a function in `POSIX.1-2017` that allocates memory as if by `malloc()`, or if the space has been deallocated by a
+call to `free()` or `realloc()`, the behavior is undefined.
+
+Any use of a pointer that refers to freed space results in undefined behavior.
+
+## Return value
+
+The `free()` function shall not return a value.
+
+## Errors
+
+No errors are defined.
+
+## Tests
+
+Tested
+
+## Known bugs
+
+None
+
+## See Also
+
+1. [Standard library functions](../README.md)
+2. [Table of Contents](../../../README.md)

libc/functions/f/fstat.part-impl.md

@@ -0,0 +1,61 @@
+# Synopsis
+
+`#include <sys/stat.h>`
+
+`int fstat(int fildes, struct stat *buf);`
+
+## Description
+
+The `fstat()` function shall obtain information about an open file associated with the file descriptor _fildes_, and
+shall write it to the area pointed to by _buf_.
+
+If _fildes_ references a shared memory object, the implementation shall update in the _stat_ structure pointed to by the
+_buf_ argument the `st_uid`, `st_gid`, `st_size`, and `st_mode` fields, and only the `S_IRUSR`, `S_IWUSR`, `S_IRGRP`,
+`S_IWGRP`, `S_IROTH`, and `S_IWOTH` file permission bits need be valid. The implementation may update other fields
+and flags.
+
+The buf argument is a pointer to a _stat_ structure, as defined in `<sys/stat.h>`, into which information is placed
+concerning the file.
+
+For all other file types defined in this volume of `POSIX.1-2017`, the structure members `st_mode`, `st_ino`, `st_dev`,
+`st_uid`, `st_gid`, `st_atim`, `st_ctim`, and `st_mtim` shall have meaningful values and the value of the `st_nlink`
+member shall be set to the number of links to the file.
+
+An implementation that provides additional or alternative file access control mechanisms may, under
+implementation-defined conditions, cause `fstat()` to fail.
+
+The `fstat()` function shall update any time-related fields (as described in XBD File Times Update), before writing into
+the _stat_ structure.
+
+## Return value
+
+Upon successful completion, `0` shall be returned. Otherwise, `-1` shall be returned and _errno_ set to indicate the
+error.
+
+## Errors
+
+The `fstat()` function shall fail if:
+
+- `[EBADF]` - The _fildes_ argument is not a valid file descriptor.
+
+- `[EIO]` - An _I/O_ error occurred while reading from the file system.
+
+- `[EOVERFLOW]` - The file size in bytes or the number of blocks allocated to the file or the file serial number cannot
+be represented correctly in the structure pointed to by _buf_.
+
+The `fstat()` function may fail if:
+
+- `[EOVERFLOW]`- One of the values is too large to store into the structure pointed to by the _buf_ argument.
+
+## Tests
+
+Untested
+
+## Known bugs
+
+None
+
+## See Also
+
+1. [Standard library functions](../README.md)
+2. [Table of Contents](../../../README.md)

libc/functions/i/isalnum.part-impl.md

@@ -0,0 +1,33 @@
+# Synopsis
+
+`#include <ctype.h>`
+
+`int isalnum(int c);`
+
+## Description
+
+The `isalnum()` function shall test whether _c_ is a character of class _alpha_ or _digit_ in the current locale.
+
+The _c_ argument is an int, the value of which the application shall ensure is representable as a `unsigned char` or
+equal to the value of the macro `EOF`. If the argument has any other value, the behavior is undefined.
+
+## Return value
+
+The `isalnum()` function shall return non-zero if _c_ is an alphanumeric character, otherwise shall return `0`.
+
+## Errors
+
+No errors are defined.
+
+## Tests
+
+Tested
+
+## Known bugs
+
+None
+
+## See Also
+
+1. [Standard library functions](../README.md)
+2. [Table of Contents](../../../README.md)

libc/functions/i/isalpha.part-impl.md

@@ -0,0 +1,33 @@
+# Synopsis
+
+`#include <ctype.h>`
+
+`int isalpha(int c);`
+
+## Description
+
+The `isalpha()` function shall test whether _c_ is a character of class _alpha_ in the current locale.
+
+The _c_ argument is an int, the value of which the application shall ensure is representable as a `unsigned char` or
+equal to the value of the macro `EOF`. If the argument has any other value, the behavior is undefined.
+
+## Return value
+
+The `isalpha()` function shall return non-zero if _c_ is an alphanumeric character, otherwise shall return `0`.
+
+## Errors
+
+No errors are defined.
+
+## Tests
+
+Tested
+
+## Known bugs
+
+None
+
+## See Also
+
+1. [Standard library functions](../README.md)
+2. [Table of Contents](../../../README.md)

libc/functions/i/isblank.part-impl.md

@@ -0,0 +1,34 @@
+# Synopsis
+
+`#include <ctype.h>`
+
+`int isblank(int c);`
+
+## Description
+
+The `isblank()` function shall test whether _c_ is a character of class _blank_ in the current locale.
+
+The _c_ argument is a type int, the value of which the application shall ensure is a character representable as a
+`unsigned char` or equal to the value of the macro `EOF`. If the argument has any other value, the behavior is
+undefined.
+
+## Return value
+
+The `isblank()` function shall return non-zero if _c_ is a `<blank>`, otherwise shall return `0`.
+
+## Errors
+
+No errors are defined.
+
+## Tests
+
+Tested
+
+## Known bugs
+
+None
+
+## See Also
+
+1. [Standard library functions](../README.md)
+2. [Table of Contents](../../../README.md)

libc/functions/i/iscntrl.part-impl.md

@@ -0,0 +1,34 @@
+# Synopsis
+
+`#include <ctype.h>`
+
+`int iscntrl(int c);`
+
+## Description
+
+The `iscntrl()` function shall test whether _c_ is a character of class _cntrl_ in the current locale.
+
+The _c_ argument is a type int, the value of which the application shall ensure is a character representable as a
+`unsigned char` or equal to the value of the macro `EOF`. If the argument has any other value, the behavior is
+undefined.
+
+## Return value
+
+The `iscntrl()` function shall return non-zero if _c_ is a control character, otherwise shall return `0`.
+
+## Errors
+
+No errors are defined.
+
+## Tests
+
+Tested
+
+## Known bugs
+
+None
+
+## See Also
+
+1. [Standard library functions](../README.md)
+2. [Table of Contents](../../../README.md)

libc/functions/i/isdigit.part-impl.md

@@ -0,0 +1,34 @@
+# Synopsis
+
+`#include <ctype.h>`
+
+`int isdigit(int c);`
+
+## Description
+
+The `isdigit()` function shall test whether _c_ is a character of class _digit_ in the current locale.
+
+The _c_ argument is an int, the value of which the application shall ensure is a character representable as a
+`unsigned char` or equal to the value of the macro `EOF`. If the argument has any other value, the behavior is
+undefined.
+
+## Return value
+
+The `isdigit()` function shall return non-zero if _c_ is decimal digit, otherwise shall return `0`.
+
+## Errors
+
+No errors are defined.
+
+## Tests
+
+Tested
+
+## Known bugs
+
+None
+
+## See Also
+
+1. [Standard library functions](../README.md)
+2. [Table of Contents](../../../README.md)