Bug 7382
| Summary: | Can't mmap a O_WRONLY fd (must be O_RDWR) | ||
|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | James Manning <jmm> |
| Component: | man-pages | Assignee: | Trond Eivind Glomsrxd <teg> |
| Status: | CLOSED RAWHIDE | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 6.1 | ||
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i386 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2000-05-29 22:00:07 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
assigned to teg Should be fixed in the next rawhide. Please note that glibc doesn't come with man pages, so you should use the info pages are a better reference. The GNU project considers man-pages obsolete (bah - much more convenient IMHO. I don't like info.) |
open("/tmp/newfile", O_WRONLY) = 3 mmap(0, 4096, PROT_WRITE, MAP_SHARED, 3, 0) = -1 EACCES (Permission denied) open("/tmp/newfile", O_RDWR) = 3 mmap(0, 4096, PROT_WRITE, MAP_SHARED, 3, 0) = 0x40013000 According to the mmap man page, EACCES when MAP_SHARED was asked and PROT_WRITE is set means that the fd was not open for writing (O_WRONLY obviously is) Since expecting O_RDWR seems reasonable, maybe the man page could simply better reflect this requirement. --- /usr/man/man2/mmap.2.orig Sat Nov 27 22:51:15 1999 +++ /usr/man/man2/mmap.2 Sat Nov 27 22:51:41 1999 @@ -128 +128 @@ -is not open for writing. +is not open in read/write (O_RDWR) mode. Sample code: #include <unistd.h> #include <sys/mman.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> int main(int argc, char **argv) { char *newfile="/tmp/newfile",*newptr; int newfd,size=getpagesize(); // guaranteed to be page-sized :) if (atoi(argv[1])) newfd=open(newfile,O_RDWR,0777); else newfd=open(newfile,O_WRONLY,0777); newptr=(char *)mmap(NULL,size,PROT_WRITE,MAP_SHARED,newfd,(int)NULL); if (newptr == MAP_FAILED) { perror("We had an mmap error"); return(1); } printf("mapped file %s size %d at %p.\n", newfile, size, newptr); strcpy(newptr,"Mary had a little lamb\n"); return(0); }