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Annotation of gcc/getpwd.c, revision 1.1

1.1     ! root        1: /* getpwd.c - get the working directory */
        !             2: 
        !             3: #include "config.h"
        !             4: 
        !             5: #include <errno.h>
        !             6: #include <sys/types.h>
        !             7: #include <sys/stat.h>
        !             8: 
        !             9: #ifndef errno
        !            10: extern int errno;
        !            11: #endif
        !            12: 
        !            13: /* Virtually every UN*X system now in common use (except for pre-4.3-tahoe
        !            14:    BSD systems) now provides getcwd as called for by POSIX.  Allow for
        !            15:    the few exceptions to the general rule here.  */
        !            16: 
        !            17: #if !(defined (POSIX) || defined (USG) || defined (VMS))
        !            18: #include <sys/param.h>
        !            19: extern char *getwd ();
        !            20: #define getcwd(buf,len) getwd(buf)
        !            21: #define GUESSPATHLEN (MAXPATHLEN + 1)
        !            22: #else /* (defined (USG) || defined (VMS)) */
        !            23: extern char *getcwd ();
        !            24: /* We actually use this as a starting point, not a limit.  */
        !            25: #define GUESSPATHLEN 100
        !            26: #endif /* (defined (USG) || defined (VMS)) */
        !            27: 
        !            28: char *getenv ();
        !            29: char *xmalloc ();
        !            30: 
        !            31: /* Get the working directory.  Use the PWD environment variable if it's
        !            32:    set correctly, since this is faster and gives more uniform answers
        !            33:    to the user.  Yield the working directory if successful; otherwise,
        !            34:    yield 0 and set errno.  */
        !            35: 
        !            36: char *
        !            37: getpwd ()
        !            38: {
        !            39:   static char *pwd;
        !            40:   static int failure_errno;
        !            41: 
        !            42:   char *p = pwd;
        !            43:   size_t s;
        !            44:   struct stat dotstat, pwdstat;
        !            45: 
        !            46:   if (!p && !(errno = failure_errno))
        !            47:     {
        !            48:       if (! ((p = getenv ("PWD")) != 0
        !            49:             && *p == '/'
        !            50:             && stat (p, &pwdstat) == 0
        !            51:             && stat (".", &dotstat) == 0
        !            52:             && dotstat.st_ino == pwdstat.st_ino
        !            53:             && dotstat.st_dev == pwdstat.st_dev))
        !            54: 
        !            55:        /* The shortcut didn't work.  Try the slow, ``sure'' way.  */
        !            56:        for (s = GUESSPATHLEN;  ! getcwd (p = xmalloc (s), s);  s *= 2)
        !            57:          {
        !            58:            int e = errno;
        !            59:            free (p);
        !            60:            if (e != ERANGE)
        !            61:              {
        !            62:                errno = failure_errno = e;
        !            63:                p = 0;
        !            64:                break;
        !            65:              }
        !            66:          }
        !            67: 
        !            68:       /* Cache the result.  This assumes that the program does
        !            69:         not invoke chdir between calls to getpwd.  */
        !            70:       pwd = p;
        !            71:     }
        !            72:   return p;
        !            73: }

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