Issue in man page readlink.2

Issue in man page readlink.2

[Helge Kreutzmann]

Without further ado, the following was found:

Issue:    the link target → link target

"#include E<lt>limits.hE<gt>\n"
"#include E<lt>stdio.hE<gt>\n"
"#include E<lt>stdlib.hE<gt>\n"
"#include E<lt>sys/stat.hE<gt>\n"
"#include E<lt>unistd.hE<gt>\n"
"\\&\n"
"int\n"
"main(int argc, char *argv[])\n"
"{\n"
"    char         *buf;\n"
"    ssize_t      nbytes, bufsiz;\n"
"    struct stat  sb;\n"
"\\&\n"
"    if (argc != 2) {\n"
"        fprintf(stderr, \"Usage: %s E<lt>pathnameE<gt>\\en\", argv[0]);\n"
"        exit(EXIT_FAILURE);\n"
"    }\n"
"\\&\n"
"    if (lstat(argv[1], &sb) == -1) {\n"
"        perror(\"lstat\");\n"
"        exit(EXIT_FAILURE);\n"
"    }\n"
"\\&\n"
"    /* Add one to the link size, so that we can determine whether\n"
"       the buffer returned by readlink() was truncated. */\n"
"\\&\n"
"    bufsiz = sb.st_size + 1;\n"
"\\&\n"
"    /* Some magic symlinks under (for example) /proc and /sys\n"
"       report \\[aq]st_size\\[aq] as zero. In that case, take PATH_MAX as\n"
"       a \"good enough\" estimate. */\n"
"\\&\n"
"    if (sb.st_size == 0)\n"
"        bufsiz = PATH_MAX;\n"
"\\&\n"
"    buf = malloc(bufsiz);\n"
"    if (buf == NULL) {\n"
"        perror(\"malloc\");\n"
"        exit(EXIT_FAILURE);\n"
"    }\n"
"\\&\n"
"    nbytes = readlink(argv[1], buf, bufsiz);\n"
"    if (nbytes == -1) {\n"
"        perror(\"readlink\");\n"
"        exit(EXIT_FAILURE);\n"
"    }\n"
"\\&\n"
"    /* Print only \\[aq]nbytes\\[aq] of \\[aq]buf\\[aq], as it doesn't contain a terminating\n"
"       null byte (\\[aq]\\e0\\[aq]). */\n"
"    printf(\"\\[aq]%s\\[aq] points to \\[aq]%.*s\\[aq]\\en\", argv[1], (int) nbytes, buf);\n"
"\\&\n"
"    /* If the return value was equal to the buffer size, then the\n"
"       the link target was larger than expected (perhaps because the\n"
"       target was changed between the call to lstat() and the call to\n"
"       readlink()). Warn the user that the returned target may have\n"
"       been truncated. */\n"
"\\&\n"
"    if (nbytes == bufsiz)\n"
"        printf(\"(Returned buffer may have been truncated)\\en\");\n"
"\\&\n"
"    free(buf);\n"
"    exit(EXIT_SUCCESS);\n"
"}\n"

Re: Issue in man page readlink.2

[Alejandro Colomar]

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On Wed, Nov 01, 2023 at 02:02:12PM +0000, Helge Kreutzmann wrote:
> Without further ado, the following was found:
> 
> Issue:    the link target → link target

Fixed:
<https://www.alejandro-colomar.es/src/alx/linux/man-pages/man-pages.git/commit/?h=contrib&id=1a2af84e62456a6ae29f1a1e1f73d761189065be>

Thanks,
Alex

> 
> "#include E<lt>limits.hE<gt>\n"
> "#include E<lt>stdio.hE<gt>\n"
> "#include E<lt>stdlib.hE<gt>\n"
> "#include E<lt>sys/stat.hE<gt>\n"
> "#include E<lt>unistd.hE<gt>\n"
> "\\&\n"
> "int\n"
> "main(int argc, char *argv[])\n"
> "{\n"
> "    char         *buf;\n"
> "    ssize_t      nbytes, bufsiz;\n"
> "    struct stat  sb;\n"
> "\\&\n"
> "    if (argc != 2) {\n"
> "        fprintf(stderr, \"Usage: %s E<lt>pathnameE<gt>\\en\", argv[0]);\n"
> "        exit(EXIT_FAILURE);\n"
> "    }\n"
> "\\&\n"
> "    if (lstat(argv[1], &sb) == -1) {\n"
> "        perror(\"lstat\");\n"
> "        exit(EXIT_FAILURE);\n"
> "    }\n"
> "\\&\n"
> "    /* Add one to the link size, so that we can determine whether\n"
> "       the buffer returned by readlink() was truncated. */\n"
> "\\&\n"
> "    bufsiz = sb.st_size + 1;\n"
> "\\&\n"
> "    /* Some magic symlinks under (for example) /proc and /sys\n"
> "       report \\[aq]st_size\\[aq] as zero. In that case, take PATH_MAX as\n"
> "       a \"good enough\" estimate. */\n"
> "\\&\n"
> "    if (sb.st_size == 0)\n"
> "        bufsiz = PATH_MAX;\n"
> "\\&\n"
> "    buf = malloc(bufsiz);\n"
> "    if (buf == NULL) {\n"
> "        perror(\"malloc\");\n"
> "        exit(EXIT_FAILURE);\n"
> "    }\n"
> "\\&\n"
> "    nbytes = readlink(argv[1], buf, bufsiz);\n"
> "    if (nbytes == -1) {\n"
> "        perror(\"readlink\");\n"
> "        exit(EXIT_FAILURE);\n"
> "    }\n"
> "\\&\n"
> "    /* Print only \\[aq]nbytes\\[aq] of \\[aq]buf\\[aq], as it doesn't contain a terminating\n"
> "       null byte (\\[aq]\\e0\\[aq]). */\n"
> "    printf(\"\\[aq]%s\\[aq] points to \\[aq]%.*s\\[aq]\\en\", argv[1], (int) nbytes, buf);\n"
> "\\&\n"
> "    /* If the return value was equal to the buffer size, then the\n"
> "       the link target was larger than expected (perhaps because the\n"
> "       target was changed between the call to lstat() and the call to\n"
> "       readlink()). Warn the user that the returned target may have\n"
> "       been truncated. */\n"
> "\\&\n"
> "    if (nbytes == bufsiz)\n"
> "        printf(\"(Returned buffer may have been truncated)\\en\");\n"
> "\\&\n"
> "    free(buf);\n"
> "    exit(EXIT_SUCCESS);\n"
> "}\n"

-- 
<https://www.alejandro-colomar.es/>

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Issue in man page readlink.2

[Helge Kreutzmann]

Without further ado, the following was found:

Issue:    B<…>size_t bufsiz → B<…size_t> I<bufsiz>

"B<ssize_t readlink(>size_t bufsiz;\n"
"B<                 const char *restrict >I<path>B<,>\n"
"B<                 char >I<buf>B<[restrict >I<bufsiz>B<], size_t >I<bufsiz>B<);>\n"

"B<ssize_t readlinkat(>size_t bufsiz;\n"
"B<                 int >I<dirfd>B<, const char *restrict >I<path>B<,>\n"
"B<                 char >I<buf>B<[restrict >I<bufsiz>B<], size_t >I<bufsiz>B<);>\n"

Issue in man page readlink.2

[Helge Kreutzmann]

Without further ado, the following was found:

Issue:    What does "like B<readlink>()" refer to? This is the man page of readlink(2)

"If I<path> is relative and I<dirfd> is the special value B<AT_FDCWD>, then "
"I<path> is interpreted relative to the current working directory of the "
"calling process (like B<readlink>())."

Re: Issue in man page readlink.2

[Alejandro Colomar]

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Hi Helge,

On Sun, Aug 24, 2025 at 02:48:51PM +0000, Helge Kreutzmann wrote:
> Without further ado, the following was found:
> 
> Issue:    What does "like B<readlink>()" refer to? This is the man page of readlink(2)

It refers to the readlink() system call.  It's in the description of the
readlinkat() system call, which is in the same page, so one refers to
the other.


Have a lovely night!
Alex

> 
> "If I<path> is relative and I<dirfd> is the special value B<AT_FDCWD>, then "
> "I<path> is interpreted relative to the current working directory of the "
> "calling process (like B<readlink>())."

-- 
<https://www.alejandro-colomar.es/>

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