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avformat/{aviobuf,avio_internal}: add max_len argument to ff_read_string_to_bprint_overwrite

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This is especially useful when reading things such as null-terminated
strings from MOV/MP4-likes, where the size of the box is known, but
not the exact size of the string.

Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>
This commit is contained in:
Jan Ekström 2021-09-20 14:51:42 +03:00 committed by Jan Ekström
parent 151f46e84d
commit 847fd8de7c
2 changed files with 25 additions and 11 deletions
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13
libavformat/avio_internal.h
View File

@ -247,14 +247,21 @@ int64_t ff_read_line_to_bprint_overwrite(AVIOContext *s, struct AVBPrint *bp);
/**
* Read a whole null-terminated string of text from AVIOContext to an AVBPrint
* buffer overwriting its contents. Stop reading after reaching a \\0 or
* EOF.
* buffer overwriting its contents. Stop reading after reaching the maximum
* length, a \\0 or EOF.
*
* @param s the read-only AVIOContext
* @param bp the AVBPrint buffer
* @param max_len the maximum length to be read from the AVIOContext.
* Negative (< 0) values signal that there is no known maximum
* length applicable. A maximum length of zero means that the
* AVIOContext is not touched, and the function returns
* with a read length of zero. In all cases the AVBprint
* is cleared.
* @return the length of the read string not including the terminating null,
* negative on error, or if the buffer becomes truncated.
*/
int64_t ff_read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp);
int64_t ff_read_string_to_bprint_overwrite(AVIOContext *s, struct AVBPrint *bp,
int64_t max_len);
#endif /* AVFORMAT_AVIO_INTERNAL_H */

23
libavformat/aviobuf.c
View File

@ -809,13 +809,17 @@ typedef enum FFBPrintReadStringMode {
} FFBPrintReadStringMode;
static int64_t read_string_to_bprint(AVIOContext *s, AVBPrint *bp,
FFBPrintReadStringMode mode)
FFBPrintReadStringMode mode,
int64_t max_len)
{
int len, end;
int64_t read = 0;
char tmp[1024];
char c;
if (!max_len)
return 0;
do {
len = 0;
do {
@ -824,10 +828,11 @@ static int64_t read_string_to_bprint(AVIOContext *s, AVBPrint *bp,
c == '\0');
if (!end)
tmp[len++] = c;
} while (!end && len < sizeof(tmp));
} while (!end && len < sizeof(tmp) &&
((max_len < 0) || (read + len < max_len)));
av_bprint_append_data(bp, tmp, len);
read += len;
} while (!end);
} while (!end && ((max_len < 0) || (read < max_len)));
if (mode == FFBPrintReadLine &&
c == '\r' && avio_r8(s) != '\n' && !avio_feof(s))
@ -843,12 +848,13 @@ static int64_t read_string_to_bprint(AVIOContext *s, AVBPrint *bp,
}
static int64_t read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp,
FFBPrintReadStringMode mode)
FFBPrintReadStringMode mode,
int64_t max_len)
{
int64_t ret;
av_bprint_clear(bp);
ret = read_string_to_bprint(s, bp, mode);
ret = read_string_to_bprint(s, bp, mode, max_len);
if (ret < 0)
return ret;
@ -860,12 +866,13 @@ static int64_t read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp,
int64_t ff_read_line_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp)
{
return read_string_to_bprint_overwrite(s, bp, FFBPrintReadLine);
return read_string_to_bprint_overwrite(s, bp, FFBPrintReadLine, -1);
}
int64_t ff_read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp)
int64_t ff_read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp,
int64_t max_len)
{
return read_string_to_bprint_overwrite(s, bp, FFBPrintReadString);
return read_string_to_bprint_overwrite(s, bp, FFBPrintReadString, max_len);
}
int avio_get_str(AVIOContext *s, int maxlen, char *buf, int buflen)