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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:17:33 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:17:33 +0000 |
commit | 5e45211a64149b3c659b90ff2de6fa982a5a93ed (patch) | |
tree | 739caf8c461053357daa9f162bef34516c7bf452 /src/port/thread.c | |
parent | Initial commit. (diff) | |
download | postgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.tar.xz postgresql-15-5e45211a64149b3c659b90ff2de6fa982a5a93ed.zip |
Adding upstream version 15.5.upstream/15.5
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/port/thread.c')
-rw-r--r-- | src/port/thread.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/src/port/thread.c b/src/port/thread.c new file mode 100644 index 0000000..23c3fbd --- /dev/null +++ b/src/port/thread.c @@ -0,0 +1,146 @@ +/*------------------------------------------------------------------------- + * + * thread.c + * + * Prototypes and macros around system calls, used to help make + * threaded libraries reentrant and safe to use from threaded applications. + * + * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group + * + * src/port/thread.c + * + *------------------------------------------------------------------------- + */ + +#include "c.h" + +#include <pwd.h> + + +/* + * Threading sometimes requires specially-named versions of functions + * that return data in static buffers, like strerror_r() instead of + * strerror(). Other operating systems use pthread_setspecific() + * and pthread_getspecific() internally to allow standard library + * functions to return static data to threaded applications. And some + * operating systems have neither. + * + * Additional confusion exists because many operating systems that + * use pthread_setspecific/pthread_getspecific() also have *_r versions + * of standard library functions for compatibility with operating systems + * that require them. However, internally, these *_r functions merely + * call the thread-safe standard library functions. + * + * For example, BSD/OS 4.3 uses Bind 8.2.3 for getpwuid(). Internally, + * getpwuid() calls pthread_setspecific/pthread_getspecific() to return + * static data to the caller in a thread-safe manner. However, BSD/OS + * also has getpwuid_r(), which merely calls getpwuid() and shifts + * around the arguments to match the getpwuid_r() function declaration. + * Therefore, while BSD/OS has getpwuid_r(), it isn't required. It also + * doesn't have strerror_r(), so we can't fall back to only using *_r + * functions for threaded programs. + * + * The current setup is to try threading in this order: + * + * use *_r function names if they exit + * (*_THREADSAFE=yes) + * use non-*_r functions if they are thread-safe + */ + +#ifndef WIN32 + +/* + * Wrapper around getpwuid() or getpwuid_r() to mimic POSIX getpwuid_r() + * behaviour, if that function is not available or required. + * + * Per POSIX, the possible cases are: + * success: returns zero, *result is non-NULL + * uid not found: returns zero, *result is NULL + * error during lookup: returns an errno code, *result is NULL + * (caller should *not* assume that the errno variable is set) + */ +static int +pqGetpwuid(uid_t uid, struct passwd *resultbuf, char *buffer, + size_t buflen, struct passwd **result) +{ +#if defined(FRONTEND) && defined(ENABLE_THREAD_SAFETY) && defined(HAVE_GETPWUID_R) + return getpwuid_r(uid, resultbuf, buffer, buflen, result); +#else + /* no getpwuid_r() available, just use getpwuid() */ + errno = 0; + *result = getpwuid(uid); + /* paranoia: ensure we return zero on success */ + return (*result == NULL) ? errno : 0; +#endif +} + +/* + * pg_get_user_name - get the name of the user with the given ID + * + * On success, the user name is returned into the buffer (of size buflen), + * and "true" is returned. On failure, a localized error message is + * returned into the buffer, and "false" is returned. + */ +bool +pg_get_user_name(uid_t user_id, char *buffer, size_t buflen) +{ + char pwdbuf[BUFSIZ]; + struct passwd pwdstr; + struct passwd *pw = NULL; + int pwerr; + + pwerr = pqGetpwuid(user_id, &pwdstr, pwdbuf, sizeof(pwdbuf), &pw); + if (pw != NULL) + { + strlcpy(buffer, pw->pw_name, buflen); + return true; + } + if (pwerr != 0) + snprintf(buffer, buflen, + _("could not look up local user ID %d: %s"), + (int) user_id, + strerror_r(pwerr, pwdbuf, sizeof(pwdbuf))); + else + snprintf(buffer, buflen, + _("local user with ID %d does not exist"), + (int) user_id); + return false; +} + +/* + * pg_get_user_home_dir - get the home directory of the user with the given ID + * + * On success, the directory path is returned into the buffer (of size buflen), + * and "true" is returned. On failure, a localized error message is + * returned into the buffer, and "false" is returned. + * + * Note that this does not incorporate the common behavior of checking + * $HOME first, since it's independent of which user_id is queried. + */ +bool +pg_get_user_home_dir(uid_t user_id, char *buffer, size_t buflen) +{ + char pwdbuf[BUFSIZ]; + struct passwd pwdstr; + struct passwd *pw = NULL; + int pwerr; + + pwerr = pqGetpwuid(user_id, &pwdstr, pwdbuf, sizeof(pwdbuf), &pw); + if (pw != NULL) + { + strlcpy(buffer, pw->pw_dir, buflen); + return true; + } + if (pwerr != 0) + snprintf(buffer, buflen, + _("could not look up local user ID %d: %s"), + (int) user_id, + strerror_r(pwerr, pwdbuf, sizeof(pwdbuf))); + else + snprintf(buffer, buflen, + _("local user with ID %d does not exist"), + (int) user_id); + return false; +} + +#endif /* !WIN32 */ |