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wget: reorder fread and poll: poll only if fread returns EAGAIN. Closes 5426

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function                                             old     new   delta
retrieve_file_data                                   451     427     -24

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2012-09-03 12:49:30 +02:00
parent 168f87c531
commit b7812ce0f7
1 changed files with 62 additions and 52 deletions
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114
networking/wget.c
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@ -444,13 +444,10 @@ static void NOINLINE retrieve_file_data(FILE *dfp)
{
#if ENABLE_FEATURE_WGET_STATUSBAR || ENABLE_FEATURE_WGET_TIMEOUT
# if ENABLE_FEATURE_WGET_TIMEOUT
unsigned second_cnt;
unsigned second_cnt = G.timeout_seconds;
# endif
struct pollfd polldata;
# if ENABLE_FEATURE_WGET_TIMEOUT
second_cnt = G.timeout_seconds;
# endif
polldata.fd = fileno(dfp);
polldata.events = POLLIN | POLLPRI;
#endif
@ -468,7 +465,7 @@ static void NOINLINE retrieve_file_data(FILE *dfp)
* which messes up progress bar and/or timeout logic.
* Because of nonblocking I/O, we need to dance
* very carefully around EAGAIN. See explanation at
* clearerr() call.
* clearerr() calls.
*/
ndelay_on(polldata.fd);
#endif
@ -476,34 +473,7 @@ static void NOINLINE retrieve_file_data(FILE *dfp)
int n;
unsigned rdsz;
rdsz = sizeof(G.wget_buf);
if (G.got_clen) {
if (G.content_len < (off_t)sizeof(G.wget_buf)) {
if ((int)G.content_len <= 0)
break;
rdsz = (unsigned)G.content_len;
}
}
#if ENABLE_FEATURE_WGET_STATUSBAR || ENABLE_FEATURE_WGET_TIMEOUT
if (safe_poll(&polldata, 1, 1000) == 0) {
# if ENABLE_FEATURE_WGET_TIMEOUT
if (second_cnt != 0 && --second_cnt == 0) {
progress_meter(PROGRESS_END);
bb_error_msg_and_die("download timed out");
}
# endif
/* Needed for "stalled" indicator */
progress_meter(PROGRESS_BUMP);
/*
* We used to loop back to poll here,
* but in chunked case, we can be here after
* fgets and it could buffer some data in dfp...
* which poll knows nothing about!
* Therefore let's try fread'ing anyway.
*/
}
/* fread internally uses read loop, which in our case
* is usually exited when we get EAGAIN.
* In this case, libc sets error marker on the stream.
@ -513,38 +483,71 @@ static void NOINLINE retrieve_file_data(FILE *dfp)
* into if (n <= 0) ...
*/
clearerr(dfp);
errno = 0;
#endif
errno = 0;
rdsz = sizeof(G.wget_buf);
if (G.got_clen) {
if (G.content_len < (off_t)sizeof(G.wget_buf)) {
if ((int)G.content_len <= 0)
break;
rdsz = (unsigned)G.content_len;
}
}
n = fread(G.wget_buf, 1, rdsz, dfp);
/* man fread:
if (n > 0) {
xwrite(G.output_fd, G.wget_buf, n);
#if ENABLE_FEATURE_WGET_STATUSBAR
G.transferred += n;
#endif
if (G.got_clen) {
G.content_len -= n;
if (G.content_len == 0)
break;
}
#if ENABLE_FEATURE_WGET_TIMEOUT
second_cnt = G.timeout_seconds;
#endif
continue;
}
/* n <= 0.
* man fread:
* If error occurs, or EOF is reached, the return value
* is a short item count (or zero).
* fread does not distinguish between EOF and error.
*/
if (n <= 0) {
#if ENABLE_FEATURE_WGET_STATUSBAR || ENABLE_FEATURE_WGET_TIMEOUT
if (errno == EAGAIN) /* poll lied, there is no data? */
continue; /* yes */
#endif
if (ferror(dfp))
if (errno != EAGAIN) {
if (ferror(dfp)) {
progress_meter(PROGRESS_END);
bb_perror_msg_and_die(bb_msg_read_error);
}
break; /* EOF, not error */
}
xwrite(G.output_fd, G.wget_buf, n);
#if ENABLE_FEATURE_WGET_TIMEOUT
second_cnt = G.timeout_seconds;
#endif
#if ENABLE_FEATURE_WGET_STATUSBAR
G.transferred += n;
#if ENABLE_FEATURE_WGET_STATUSBAR || ENABLE_FEATURE_WGET_TIMEOUT
/* It was EAGAIN. There is no data. Wait up to one second
* then abort if timed out, or update the bar and try reading again.
*/
if (safe_poll(&polldata, 1, 1000) == 0) {
# if ENABLE_FEATURE_WGET_TIMEOUT
if (second_cnt != 0 && --second_cnt == 0) {
progress_meter(PROGRESS_END);
bb_error_msg_and_die("download timed out");
}
# endif
/* We used to loop back to poll here,
* but there is no great harm in letting fread
* to try reading anyway.
*/
}
/* Need to do it _every_ second for "stalled" indicator
* to be shown properly.
*/
progress_meter(PROGRESS_BUMP);
#endif
if (G.got_clen) {
G.content_len -= n;
if (G.content_len == 0)
break;
}
}
} /* while (reading data) */
#if ENABLE_FEATURE_WGET_STATUSBAR || ENABLE_FEATURE_WGET_TIMEOUT
clearerr(dfp);
ndelay_off(polldata.fd); /* else fgets can get very unhappy */
@ -560,6 +563,13 @@ static void NOINLINE retrieve_file_data(FILE *dfp)
if (G.content_len == 0)
break; /* all done! */
G.got_clen = 1;
/*
* Note that fgets may result in some data being buffered in dfp.
* We loop back to fread, which will retrieve this data.
* Also note that code has to be arranged so that fread
* is done _before_ one-second poll wait - poll doesn't know
* about stdio buffering and can result in spurious one second waits!
*/
}
/* If -c failed, we restart from the beginning,