1 /* strerror.c --- POSIX compatible system error routine 2 3 Copyright (C) 2007-2011 Free Software Foundation, Inc. 4 5 This program is free software: you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17 18 #include <config.h> 19 20 /* Specification. */ 21 #include <string.h> 22 23 #include <errno.h> 24 #include <stdio.h> 25 #include <stdlib.h> 26 #include <string.h> 27 28 #include "intprops.h" 29 #include "strerror-override.h" 30 #include "verify.h" 31 32 /* Use the system functions, not the gnulib overrides in this file. */ 33 #undef sprintf 34 35 char * 36 strerror (int n) 37 #undef strerror 38 { 39 static char buf[STACKBUF_LEN]; 40 size_t len; 41 42 /* Cast away const, due to the historical signature of strerror; 43 callers should not be modifying the string. */ 44 const char *msg = strerror_override (n); 45 if (msg) 46 return (char *) msg; 47 48 /* FreeBSD rejects 0; see http://austingroupbugs.net/view.php?id=382. 49 MacOS X 10.5 does not distinguish 0 from -1. */ 50 if (n) 51 msg = strerror (n); 52 else 53 { 54 int saved_errno = errno; 55 errno = 0; 56 msg = strerror (n); 57 if (errno || (msg && 58 (strstr (msg, "nknown") || strstr (msg, "ndefined")))) 59 msg = "Success"; 60 errno = saved_errno; 61 } 62 63 /* Our strerror_r implementation might use the system's strerror 64 buffer, so all other clients of strerror have to see the error 65 copied into a buffer that we manage. This is not thread-safe, 66 even if the system strerror is, but portable programs shouldn't 67 be using strerror if they care about thread-safety. */ 68 if (!msg || !*msg) 69 { 70 static char const fmt[] = "Unknown error %d"; 71 verify (sizeof buf >= sizeof (fmt) + INT_STRLEN_BOUND (n)); 72 sprintf (buf, fmt, n); 73 errno = EINVAL; 74 return buf; 75 } 76 77 /* Fix STACKBUF_LEN if this ever aborts. */ 78 len = strlen (msg); 79 if (sizeof buf <= len) 80 abort (); 81 82 return memcpy (buf, msg, len + 1); 83 } 84