2 * <errno.h> wrapper functions.
12 /* DEPRECATED: Use the Stdlib version instead */
14 Mono_Posix_Syscall_SetLastError (int error_number)
20 Mono_Posix_Stdlib_SetLastError (int error_number)
25 #ifdef HAVE_STRERROR_R
28 * There are two versions of strerror_r:
29 * - the GNU version: char *strerror_r (int errnum, char *buf, size_t n);
30 * - the XPG version: int strerror_r (int errnum, char *buf, size_t n);
32 * Ideally I could stick with the XPG version, but we need to support
33 * Red Hat 9, which only supports the GNU version.
35 * Furthermore, I do NOT want to export the GNU version in Mono.Posix.dll,
36 * as that's supposed to contain *standard* function definitions (give or
37 * take a few GNU extensions). Portability trumps all.
39 * Consequently, we export the functionality of the XPG version.
40 * Internally, we se the GNU version if _GNU_SOURCE is defined, otherwise
41 * we assume that the XPG version is present.
45 #define mph_min(x,y) ((x) <= (y) ? (x) : (y))
47 /* If you pass an invalid errno value to glibc 2.3.2's strerror_r, you get
48 * back the string "Unknown error" with the error value appended. */
49 static const char mph_unknown[] = "Unknown error ";
52 * Translate the GNU semantics to the XPG semantics.
54 * From reading the (RH9-using) GLibc 2.3.2 sysdeps/generic/_strerror.c,
55 * we can say the following:
56 * - If errnum is a valid error number, a pointer to a constant string is
57 * returned. Thus, the prototype *lies* (it's not really a char*).
58 * `buf' is unchanged (WTF?).
59 * - If errnum is an *invalid* error number, an error message is copied
60 * into `buf' and `buf' is returned. The error message returned is
61 * "Unknown error %i", where %i is the input errnum.
63 * Meanwhile, XPG always modifies `buf' if there's enough space, and either
64 * returns 0 (success) or -1 (error) with errno = EINVAL (bad errnum) or
65 * ERANGE (`buf' isn't big enough). Also, GLibc 2.3.3 (which has the XPG
66 * version) first checks the validity of errnum first, then does the copy.
68 * Assuming that the GNU implementation doesn't change much (ha!), we can
69 * check for EINVAL by comparing the strerror_r return to `buf', OR by
70 * comparing the return value to "Uknown error". (This assumes that
71 * strerror_r will always only return the input buffer for errors.)
73 * Check for ERANGE by comparing the string length returned by strerror_r to
76 * Then pray that this actually works...
79 Mono_Posix_Syscall_strerror_r (int errnum, char *buf, mph_size_t n)
82 char ebuf [sizeof(mph_unknown)];
86 mph_return_if_size_t_overflow (n);
88 /* first, check for valid errnum */
89 r = strerror_r (errnum, ebuf, sizeof(ebuf));
93 strncmp (r, mph_unknown, mph_min (len, sizeof(mph_unknown))) == 0) {
98 /* valid errnum (we hope); is buffer big enough? */
100 if ((len+1) > blen) {
105 strncpy (buf, r, len);
111 #else /* !def _GNU_SOURCE */
114 Mono_Posix_Syscall_strerror_r (int errnum, char *buf, mph_size_t n)
116 mph_return_if_size_t_overflow (n);
117 return strerror_r (errnum, buf, (size_t) n);
120 #endif /* def _GNU_SOURCE */
122 #endif /* def HAVE_STRERROR_R */