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libc: Check for a compatible mode in fdopen()
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apio 2023-03-28 20:56:00 +02:00
parent 6239ed83c7
commit 0d54d0ece1
Signed by: apio
GPG Key ID: B8A7D06E42258954
1 changed files with 17 additions and 3 deletions
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20
libc/src/stdio.cpp
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@ -29,6 +29,22 @@ static int fopen_parse_mode(const char* mode)
return result;
}
static int fdopen_check_compatible_mode(int fd, int new_flags)
{
int old_flags = fcntl(fd, F_GETFL);
if (old_flags < 0) return -1;
int old_mode = old_flags & O_ACCMODE;
int new_mode = new_flags & O_ACCMODE;
if ((old_mode & new_mode) != new_mode)
{
errno = EINVAL;
return -1;
}
return 0;
}
extern "C"
{
FILE* fopen(const char* path, const char* mode)
@ -59,9 +75,7 @@ extern "C"
if ((flags = fopen_parse_mode(mode)) < 0) return nullptr;
// FIXME: We do verify that fd is valid, but not that the mode is compatible.
long rc = lseek(fd, 0, SEEK_CUR);
if (rc < 0) return nullptr;
if (fdopen_check_compatible_mode(fd, flags) < 0) return nullptr;
FILE* f = (FILE*)malloc(sizeof(FILE));
if (!f) { return nullptr; }