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[FIX] file_functions: three integer conversions in the read path (truncated seek, unsigned underflow, signed/unsigned compare) #2325

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Merged
cfsmp3 merged 1 commit into from
Aug 15, 2026
Merged

[FIX] file_functions: three integer conversions in the read path (truncated seek, unsigned underflow, signed/unsigned compare) #2325

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18 changes: 15 additions & 3 deletions src/lib_ccx/file_functions.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,10 @@ int iResult = 0;

LLONG get_file_size(int in)
{
int ret = 0;
/* LSEEK returns a 64-bit offset. Storing it in an int truncated the result, so a
successful seek back to a position at or beyond 2 GB could land on a negative
value and be reported as a failure. */
LLONG ret = 0;
LLONG current = LSEEK(in, 0, SEEK_CUR);
LLONG length = LSEEK(in, 0, SEEK_END);
if (current < 0 || length < 0)
Expand Down Expand Up @@ -344,7 +347,7 @@ size_t buffered_read_opt(struct ccx_demuxer *ctx, unsigned char *buffer, size_t
// for the data to come up
sleepandchecktimeout(seconds);
}
size_t ready = ctx->bytesinbuffer - ctx->filebuffer_pos;
size_t ready = buffered_bytes_left(ctx);
if (ready == 0) // We really need to read more
{
if (!ccx_options.buffer_input)
Expand Down Expand Up @@ -417,7 +420,16 @@ size_t buffered_read_opt(struct ccx_demuxer *ctx, unsigned char *buffer, size_t
{
/* If live stream, don't try to switch - acknowledge eof here as it won't
cause a loop end */
if (ccx_options.live_stream || ((struct lib_ccx_ctx *)ctx->parent)->inputsize <= origin_buffer_size || !(ccx_options.binary_concat && switch_to_next_file(ctx->parent, copied)))
/* inputsize is a signed 64-bit size while origin_buffer_size is unsigned,
so the comparison used to convert inputsize to unsigned. A negative
inputsize -- what get_filesize() reports when the size could not be
determined -- turned into a huge value, and the test silently read as
"the input is enormous". Say what is meant instead. An unknown size
still does not count as fitting in one read, so behaviour is unchanged. */
LLONG parent_inputsize = ((struct lib_ccx_ctx *)ctx->parent)->inputsize;
int input_fits_in_one_read = parent_inputsize >= 0 &&
(uint64_t)parent_inputsize <= (uint64_t)origin_buffer_size;
if (ccx_options.live_stream || input_fits_in_one_read || !(ccx_options.binary_concat && switch_to_next_file(ctx->parent, copied)))
eof = 1;
}
ctx->filebuffer_pos = keep;
Expand Down
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