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From: "chianshin at gmail dot com" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sources.redhat.com Subject: [Bug libc/12825] New: write function returning -1 in cookie_io_functions_t will crash the program Date: Mon, 30 May 2011 18:50:00 -0000 [thread overview] Message-ID: <bug-12825-131@http.sourceware.org/bugzilla/> (raw) http://sourceware.org/bugzilla/show_bug.cgi?id=12825 Summary: write function returning -1 in cookie_io_functions_t will crash the program Product: glibc Version: unspecified Status: NEW Severity: critical Priority: P2 Component: libc AssignedTo: drepper.fsp@gmail.com ReportedBy: chianshin@gmail.com This program which is from http://www.kernel.org/doc/man-pages/online/pages/man3/fopencookie.3.html The webpage also stated that if error happens, write should return -1; But I found that returning -1 will crash the program. The reason is explained in this bugzilla report. http://sourceware.org/bugzilla/show_bug.cgi?id=2074 But glibc did fix the above bug. Linux driver will also return negative value when error happens, Does it have the same problem as the program here? //=========================================================== #define _GNU_SOURCE #include <sys/types.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include "assert.h" #define INIT_BUF_SIZE 4 struct memfile_cookie { char *buf; /* Dynamically sized buffer for data */ size_t allocated; /* Size of buf */ size_t endpos; /* Number of characters in buf */ off_t offset; /* Current file offset in buf */ }; ssize_t memfile_write(void *c, const char *buf, size_t size) { return -1; } ssize_t memfile_read(void *c, char *buf, size_t size) { assert(0); return 0; } int memfile_seek(void *c, off64_t *offset, int whence) { assert(0); return 0; } int memfile_close(void *c) { struct memfile_cookie *cookie = c; free(cookie->buf); cookie->allocated = 0; cookie->buf = NULL; return 0; } int main(int argc, char *argv[]) { cookie_io_functions_t memfile_func = { .read = memfile_read, .write = memfile_write, .seek = memfile_seek, .close = memfile_close }; FILE *fp; struct memfile_cookie mycookie; /* Set up the cookie before calling fopencookie() */ mycookie.buf = malloc(INIT_BUF_SIZE); if (mycookie.buf == NULL) { perror("malloc"); exit(EXIT_FAILURE); } mycookie.allocated = INIT_BUF_SIZE; mycookie.offset = 0; mycookie.endpos = 0; fp = fopencookie(&mycookie,"w+", memfile_func); if (fp == NULL) { perror("fopencookie"); exit(EXIT_FAILURE); } enum CONST_T{BUFF_SIZE=9000}; char buff[BUFF_SIZE]={"good out"}; size_t out=fwrite(buff,BUFF_SIZE,1,fp); fprintf(stderr,"output size:%d\n",out); exit(EXIT_SUCCESS); } //=========================================================== -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
next reply other threads:[~2011-05-30 18:50 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-05-30 18:50 chianshin at gmail dot com [this message] 2011-05-30 18:55 ` [Bug libc/12825] " chianshin at gmail dot com 2011-05-30 22:36 ` drepper.fsp at gmail dot com 2011-05-30 23:08 ` chianshin at gmail dot com 2014-06-13 14:41 ` fweimer at redhat dot com
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