From Craig Silverstein: delete the output file first if it exists and

is non-empty.
This commit is contained in:
Ian Lance Taylor 2007-10-10 06:29:10 +00:00
parent cf0d1c8e4d
commit 4e9d858638
1 changed files with 20 additions and 0 deletions

View File

@ -27,6 +27,7 @@
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <algorithm>
#include "parameters.h"
@ -1672,6 +1673,25 @@ Output_file::open(off_t file_size)
{
this->file_size_ = file_size;
// Unlink the file first; otherwise the open() may fail if the file
// is busy (e.g. it's an executable that's currently being executed).
//
// However, the linker may be part of a system where a zero-length
// file is created for it to write to, with tight permissions (gcc
// 2.95 did something like this). Unlinking the file would work
// around those permission controls, so we only unlink if the file
// has a non-zero size. We also unlink only regular files to avoid
// trouble with directories/etc.
//
// If we fail, continue; this command is merely a best-effort attempt
// to improve the odds for open().
// FIXME: unlink the file if it's a symlink, even a symlink to a dir.
// Or do we want to follow the symlink and unlink its target?
struct stat s;
if (::stat(this->name_, &s) == 0 && s.st_size != 0 && S_ISREG(s.st_mode))
::unlink(this->name_);
int mode = parameters->output_is_object() ? 0666 : 0777;
int o = ::open(this->name_, O_RDWR | O_CREAT | O_TRUNC, mode);
if (o < 0)