On 21.11.23 08:36, Sascha Hauer wrote:
> On Mon, Nov 20, 2023 at 09:37:49AM +0100, Ahmad Fatoum wrote:
>> Files opened with O_TMPFILE have no name, so read_file can't be used
>> with them. Therefore add a read_fd function, which slurps all a file's
>> contents into a buffer.
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
>> ---
>> include/libfile.h | 2 ++
>> lib/libfile.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 46 insertions(+)
>>
>> diff --git a/include/libfile.h b/include/libfile.h
>> index a353ccfa9ea9..423e7ffec5b7 100644
>> --- a/include/libfile.h
>> +++ b/include/libfile.h
>> @@ -12,6 +12,8 @@ char *read_file_line(const char *fmt, ...);
>>
>> void *read_file(const char *filename, size_t *size);
>>
>> +void *read_fd(int fd, size_t *size);
>> +
>> int read_file_2(const char *filename, size_t *size, void **outbuf,
>> loff_t max_size);
>>
>> diff --git a/lib/libfile.c b/lib/libfile.c
>> index e53ba08415a2..c257baaa2733 100644
>> --- a/lib/libfile.c
>> +++ b/lib/libfile.c
>> @@ -306,6 +306,50 @@ void *read_file(const char *filename, size_t *size)
>> }
>> EXPORT_SYMBOL(read_file);
>>
>> +/**
>> + * read_fd - read from a file descriptor to an allocated buffer
>> + * @filename: The file descriptor to read
>> + * @size: After successful return contains the size of the file
>> + *
>> + * This function reads a file descriptor from offset 0 until EOF to an
>> + * allocated buffer.
>> + *
>> + * Return: The buffer containing the file or NULL on failure
>> + */
>> +void *read_fd(int fd, size_t *out_size)
>> +{
>> + off_t off;
>> + ssize_t ret;
>> + size_t size;
>> + void *buf;
>> +
>> + off = lseek(fd, SEEK_CUR, 0);
>
> You lseek to the current position. It seems you are trying to determine
> the size of the file, so did you mean to use SEEK_END?
>
> You could use fstat() instead. With that you could also correctly handle
> FILE_SIZE_STREAM.
Will use fstat, thanks.
>
>> + if (off >= 0) {
>> + size = off;
>> + off = lseek(fd, SEEK_SET, 0);
>> + }
>> + if (off < 0) {
>> + ret = off;
>> + goto close_fd;
>> + }
>> +
>> + buf = malloc(size + 3);
>> + ret = read_full(fd, buf, size);
>
> You can use pread_full() here to avoid having to lseek to the beginning
> of the file.
Ok, will do.
>
>> + if (ret < 0) {
>> + free(buf);
>> + goto close_fd;
>> + }
>> +
>> + memset(&buf[size], '\0', 3);
>> + *out_size = size;
>> +
>> +close_fd:
>> + close(fd);
>> +
>> + return ret < 0 ? NULL : buf;
>
> Return an error pointer or an error integer and pass buf as argument?
I want it to return a buffer like read_file does. I think that would
be the least surprising API.
Cheers,
Ahmad
>
> Sascha
>
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