143 lines
3.9 KiB
C
143 lines
3.9 KiB
C
/*
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* <errno.h> wrapper functions.
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*/
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#include <errno.h>
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#include <string.h>
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#include "map.h"
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#include "mph.h"
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#include <stdio.h>
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G_BEGIN_DECLS
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void
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Mono_Posix_Stdlib_SetLastError (int error_number)
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{
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errno = error_number;
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}
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#ifdef HAVE_STRERROR_R
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/*
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* There are two versions of strerror_r:
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* - the GNU version: char *strerror_r (int errnum, char *buf, size_t n);
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* - the XPG version: int strerror_r (int errnum, char *buf, size_t n);
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*
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* Ideally I could stick with the XPG version, but we need to support
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* Red Hat 9, which only supports the GNU version.
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*
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* Furthermore, I do NOT want to export the GNU version in Mono.Posix.dll,
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* as that's supposed to contain *standard* function definitions (give or
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* take a few GNU extensions). Portability trumps all.
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*
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* Consequently, we export the functionality of the XPG version.
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* Internally, we se the GNU version if _GNU_SOURCE is defined, otherwise
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* we assume that the XPG version is present.
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*/
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#ifdef _GNU_SOURCE && !PLATFORM_ANDROID
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#define mph_min(x,y) ((x) <= (y) ? (x) : (y))
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/* If you pass an invalid errno value to glibc 2.3.2's strerror_r, you get
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* back the string "Unknown error" with the error value appended. */
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static const char mph_unknown[] = "Unknown error ";
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/*
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* Translate the GNU semantics to the XPG semantics.
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*
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* From reading the (RH9-using) GLibc 2.3.2 sysdeps/generic/_strerror.c,
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* we can say the following:
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* - If errnum is a valid error number, a pointer to a constant string is
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* returned. Thus, the prototype *lies* (it's not really a char*).
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* `buf' is unchanged (WTF?).
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* - If errnum is an *invalid* error number, an error message is copied
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* into `buf' and `buf' is returned. The error message returned is
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* "Unknown error %i", where %i is the input errnum.
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*
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* Meanwhile, XPG always modifies `buf' if there's enough space, and either
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* returns 0 (success) or -1 (error) with errno = EINVAL (bad errnum) or
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* ERANGE (`buf' isn't big enough). Also, GLibc 2.3.3 (which has the XPG
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* version) first checks the validity of errnum first, then does the copy.
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*
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* Assuming that the GNU implementation doesn't change much (ha!), we can
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* check for EINVAL by comparing the strerror_r return to `buf', OR by
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* comparing the return value to "Uknown error". (This assumes that
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* strerror_r will always only return the input buffer for errors.)
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*
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* Check for ERANGE by comparing the string length returned by strerror_r to
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* `n'.
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*
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* Then pray that this actually works...
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*/
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gint32
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Mono_Posix_Syscall_strerror_r (int errnum, char *buf, mph_size_t n)
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{
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char *r;
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char ebuf [sizeof(mph_unknown)];
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size_t len;
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size_t blen;
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mph_return_if_size_t_overflow (n);
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/* first, check for valid errnum */
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#if PLATFORM_ANDROID
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/* Android NDK defines _GNU_SOURCE but strerror_r follows the XSI semantics
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* not the GNU one. XSI version returns an integer, as opposed to the GNU one
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* which returns pointer to the buffer.
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*/
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if (strerror_r (errnum, ebuf, sizeof(ebuf)) == -1) {
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/* XSI strerror_r will return -1 if errno is set, but if we leave the value
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* alone it breaks Mono.Posix StdioFileStream tests, so we'll ignore the value
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* and set errno as below
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*/
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errno = EINVAL;
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return -1;
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}
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r = ebuf;
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#else
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r = strerror_r (errnum, ebuf, sizeof(ebuf));
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#endif
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if (!r) {
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errno = EINVAL;
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return -1;
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}
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len = strlen (r);
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if (r == ebuf ||
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strncmp (r, mph_unknown, mph_min (len, sizeof(mph_unknown))) == 0) {
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errno = EINVAL;
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return -1;
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}
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/* valid errnum (we hope); is buffer big enough? */
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blen = (size_t) n;
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if ((len+1) > blen) {
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errno = ERANGE;
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return -1;
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}
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strncpy (buf, r, len);
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buf[len] = '\0';
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return 0;
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}
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#else /* !def _GNU_SOURCE */
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gint32
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Mono_Posix_Syscall_strerror_r (int errnum, char *buf, mph_size_t n)
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{
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mph_return_if_size_t_overflow (n);
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return strerror_r (errnum, buf, (size_t) n);
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}
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#endif /* def _GNU_SOURCE */
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#endif /* def HAVE_STRERROR_R */
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G_END_DECLS
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/*
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* vim: noexpandtab
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*/
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