openat_proc_name: port to OS/2 kLIBC

OS/2 kLIBC provides a function to retrive a path from a fd. Use it
instead of /proc/self/fd.
* lib/openat-proc.c (openat_proc_name):
Don't assume file name length is less than INT_MAX.
Port to OS/2 kLIBC with __libc_Back_ioFHToPath().

1 files changed, 88 insertions, 56 deletions

diff --git a/lib/openat-proc.c b/lib/openat-proc.c
index 15a8c799c8..6fba6c2bbf 100644
--- a/lib/openat-proc.c
+++ b/lib/openat-proc.c
@@ -30,24 +30,21 @@
 #include <string.h>
 #include <unistd.h>
 
-#include "intprops.h"
-
-#define PROC_SELF_FD_FORMAT "/proc/self/fd/%d/%s"
-
-#define PROC_SELF_FD_NAME_SIZE_BOUND(len) \
-  (sizeof PROC_SELF_FD_FORMAT - sizeof "%d%s" \
-   + INT_STRLEN_BOUND (int) + (len) + 1)
+#ifdef __KLIBC__
+# include <InnoTekLIBC/backend.h>
+#endif
 
+#include "intprops.h"
 
-/* Set BUF to the expansion of PROC_SELF_FD_FORMAT, using FD and FILE
-   respectively for %d and %s.  If successful, return BUF if the
-   result fits in BUF, dynamically allocated memory otherwise.  But
-   return NULL if /proc is not reliable, either because the operating
-   system support is lacking or because memory is low.  */
+/* Set BUF to the name of the subfile of the directory identified by
+   FD, where the subfile is named FILE.  If successful, return BUF if
+   the result fits in BUF, dynamically allocated memory otherwise.
+   Return NULL (setting errno) on error.  */
 char *
 openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file)
 {
-  static int proc_status = 0;
+  char *result = buf;
+  int dirlen;
 
   /* Make sure the caller gets ENOENT when appropriate.  */
   if (!*file)
@@ -56,47 +53,82 @@ openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file)
       return buf;
     }
 
-  if (! proc_status)
-    {
-      /* Set PROC_STATUS to a positive value if /proc/self/fd is
-         reliable, and a negative value otherwise.  Solaris 10
-         /proc/self/fd mishandles "..", and any file name might expand
-         to ".." after symbolic link expansion, so avoid /proc/self/fd
-         if it mishandles "..".  Solaris 10 has openat, but this
-         problem is exhibited on code that built on Solaris 8 and
-         running on Solaris 10.  */
-
-      int proc_self_fd = open ("/proc/self/fd",
-                               O_SEARCH | O_DIRECTORY | O_NOCTTY | O_NONBLOCK);
-      if (proc_self_fd < 0)
-        proc_status = -1;
-      else
-        {
-          /* Detect whether /proc/self/fd/%i/../fd exists, where %i is the
-             number of a file descriptor open on /proc/self/fd.  On Linux,
-             that name resolves to /proc/self/fd, which was opened above.
-             However, on Solaris, it may resolve to /proc/self/fd/fd, which
-             cannot exist, since all names in /proc/self/fd are numeric.  */
-          char dotdot_buf[PROC_SELF_FD_NAME_SIZE_BOUND (sizeof "../fd" - 1)];
-          sprintf (dotdot_buf, PROC_SELF_FD_FORMAT, proc_self_fd, "../fd");
-          proc_status = access (dotdot_buf, F_OK) ? -1 : 1;
-          close (proc_self_fd);
-        }
-    }
-
-  if (proc_status < 0)
-    return NULL;
-  else
-    {
-      size_t bufsize = PROC_SELF_FD_NAME_SIZE_BOUND (strlen (file));
-      char *result = buf;
-      if (OPENAT_BUFFER_SIZE < bufsize)
-        {
-          result = malloc (bufsize);
-          if (! result)
-            return NULL;
-        }
-      sprintf (result, PROC_SELF_FD_FORMAT, fd, file);
-      return result;
-    }
+#ifndef __KLIBC__
+# define PROC_SELF_FD_FORMAT "/proc/self/fd/%d/"
+  {
+    enum {
+      PROC_SELF_FD_DIR_SIZE_BOUND
+        = (sizeof PROC_SELF_FD_FORMAT - (sizeof "%d" - 1)
+           + INT_STRLEN_BOUND (int))
+    };
+
+    static int proc_status = 0;
+    if (! proc_status)
+      {
+        /* Set PROC_STATUS to a positive value if /proc/self/fd is
+           reliable, and a negative value otherwise.  Solaris 10
+           /proc/self/fd mishandles "..", and any file name might expand
+           to ".." after symbolic link expansion, so avoid /proc/self/fd
+           if it mishandles "..".  Solaris 10 has openat, but this
+           problem is exhibited on code that built on Solaris 8 and
+           running on Solaris 10.  */
+
+        int proc_self_fd = open ("/proc/self/fd",
+                                 O_SEARCH | O_DIRECTORY | O_NOCTTY | O_NONBLOCK);
+        if (proc_self_fd < 0)
+          proc_status = -1;
+        else
+          {
+            /* Detect whether /proc/self/fd/%i/../fd exists, where %i is the
+               number of a file descriptor open on /proc/self/fd.  On Linux,
+               that name resolves to /proc/self/fd, which was opened above.
+               However, on Solaris, it may resolve to /proc/self/fd/fd, which
+               cannot exist, since all names in /proc/self/fd are numeric.  */
+            char dotdot_buf[PROC_SELF_FD_DIR_SIZE_BOUND + sizeof "../fd" - 1];
+            sprintf (dotdot_buf, PROC_SELF_FD_FORMAT "../fd", proc_self_fd);
+            proc_status = access (dotdot_buf, F_OK) ? -1 : 1;
+            close (proc_self_fd);
+          }
+      }
+
+    if (proc_status < 0)
+      return NULL;
+    else
+      {
+        size_t bufsize = PROC_SELF_FD_DIR_SIZE_BOUND + strlen (file);
+        if (OPENAT_BUFFER_SIZE < bufsize)
+          {
+            result = malloc (bufsize);
+            if (! result)
+              return NULL;
+          }
+
+        dirlen = sprintf (result, PROC_SELF_FD_FORMAT, fd);
+      }
+  }
+#else
+  /* OS/2 kLIBC provides a function to retrieve a path from a fd.  */
+  {
+    char dir[_MAX_PATH];
+    size_t bufsize;
+
+    if (__libc_Back_ioFHToPath (fd, dir, sizeof dir))
+      return NULL;
+
+    dirlen = strlen (dir);
+    bufsize = dirlen + 1 + strlen (file) + 1; /* 1 for '/', 1 for null */
+    if (OPENAT_BUFFER_SIZE < bufsize)
+      {
+        result = malloc (bufsize);
+        if (! result)
+          return NULL;
+      }
+
+    strcpy (result, dir);
+    result[dirlen] = '/';
+  }
+#endif
+
+  strcpy (result + dirlen, file);
+  return result;
 }