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Workaround file truncation in write-only mode

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bzt 2022-01-16 00:32:15 +01:00
parent d5125beff5
commit 9d1e438711
1 changed files with 16 additions and 6 deletions
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22
uefi/stdio.c
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@ -153,8 +153,8 @@ int __remove (const char_t *__filename, int isdir)
efi_guid_t infGuid = EFI_FILE_INFO_GUID;
efi_file_info_t info;
uintn_t fsiz = (uintn_t)sizeof(efi_file_info_t), i;
/* little hack to support read and write mode for Delete() without create mode */
FILE *f = fopen(__filename, CL("@"));
/* little hack to support read and write mode for Delete() and stat() without create mode or checks */
FILE *f = fopen(__filename, CL("*"));
if(errno)
return 1;
if(!f || f == stdin || f == stdout || f == stderr || (__ser && f == (FILE*)__ser)) {
@ -207,7 +207,8 @@ FILE *fopen (const char_t *__filename, const char_t *__modes)
wchar_t wcname[BUFSIZ];
#endif
errno = 0;
if(!__filename || !*__filename || !__modes || !*__modes) {
if(!__filename || !*__filename || !__modes || (__modes[0] != CL('r') && __modes[0] != CL('w') && __modes[0] != CL('a') &&
__modes[0] != CL('*')) || (__modes[1] != CL('d') || __modes[1] != CL('+'))) {
errno = EINVAL;
return NULL;
}
@ -274,7 +275,9 @@ FILE *fopen (const char_t *__filename, const char_t *__modes)
}
ret = (FILE*)malloc(sizeof(FILE));
if(!ret) return NULL;
/* normally write means read,write,create. But for remove (internal '@' mode), we need read,write without create */
/* normally write means read,write,create. But for remove (internal '*' mode), we need read,write without create
* also mode 'w' in POSIX means write-only (without read), but that's not working on certain firmware, we must
* pass read too. This poses a problem of truncating a write-only file, see issue #26, we have to do that manually */
#ifndef UEFI_NO_UTF8
mbstowcs((wchar_t*)&wcname, __filename, BUFSIZ - 1);
status = __root_dir->Open(__root_dir, &ret, (wchar_t*)&wcname,
@ -282,13 +285,13 @@ FILE *fopen (const char_t *__filename, const char_t *__modes)
status = __root_dir->Open(__root_dir, &ret, (wchar_t*)__filename,
#endif
__modes[0] == CL('w') || __modes[0] == CL('a') ? (EFI_FILE_MODE_WRITE | EFI_FILE_MODE_READ | EFI_FILE_MODE_CREATE) :
EFI_FILE_MODE_READ | (__modes[0] == CL('@') ? EFI_FILE_MODE_WRITE : 0),
EFI_FILE_MODE_READ | (__modes[0] == CL('*') || __modes[1] == CL('+') ? EFI_FILE_MODE_WRITE : 0),
__modes[1] == CL('d') ? EFI_FILE_DIRECTORY : 0);
if(EFI_ERROR(status)) {
err: __stdio_seterrno(status);
free(ret); return NULL;
}
if(__modes[0] == CL('@')) return ret;
if(__modes[0] == CL('*')) return ret;
status = ret->GetInfo(ret, &infGuid, &fsiz, &info);
if(EFI_ERROR(status)) goto err;
if(__modes[1] == CL('d') && !(info.Attribute & EFI_FILE_DIRECTORY)) {
@ -298,6 +301,13 @@ err: __stdio_seterrno(status);
ret->Close(ret); free(ret); errno = EISDIR; return NULL;
}
if(__modes[0] == CL('a')) fseek(ret, 0, SEEK_END);
if(__modes[0] == CL('w')) {
/* manually truncate file size
* See https://github.com/tianocore/edk2/blob/master/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
* function FileHandleSetSize */
info.FileSize = 0;
ret->SetInfo(ret, &infGuid, fsiz, &info);
}
return ret;
}