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Avoid pathological behavior in OpenBSD's fread.

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Bug: https://code.google.com/p/android/issues/detail?id=81155
Bug: 18556607
Change-Id: Idc60976b79610e2202cc42dc393dcb4ca6c42e05
This commit is contained in:
Elliott Hughes
2014-12-01 16:13:30 -08:00
parent 5cd127d3aa
commit 20841a137b
3 changed files with 49 additions and 2 deletions
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2
libc/Android.mk
View File

@@ -58,6 +58,7 @@ libc_common_src_files := \
bionic/sigsetmask.c \
bionic/system_properties_compat.c \
stdio/findfp.c \
stdio/fread.c \
stdio/snprintf.c\
stdio/sprintf.c \
stdio/stdio_ext.cpp \
@@ -406,7 +407,6 @@ libc_upstream_openbsd_src_files := \
upstream-openbsd/lib/libc/stdio/fputs.c \
upstream-openbsd/lib/libc/stdio/fputwc.c \
upstream-openbsd/lib/libc/stdio/fputws.c \
upstream-openbsd/lib/libc/stdio/fread.c \
upstream-openbsd/lib/libc/stdio/freopen.c \
upstream-openbsd/lib/libc/stdio/fscanf.c \
upstream-openbsd/lib/libc/stdio/fseek.c \

18
libc/upstream-openbsd/lib/libc/stdio/fread.c → libc/stdio/fread.c
View File

@@ -68,7 +68,23 @@ fread(void *buf, size_t size, size_t count, FILE *fp)
fp->_r = 0;
total = resid;
p = buf;
while (resid > (r = fp->_r)) {
// BEGIN android-added
// Avoid pathological behavior on unbuffered files. OpenBSD
// will loop reading one byte then memcpying one byte!
if ((fp->_flags & __SNBF) != 0) {
// We know if we're unbuffered that our buffer is empty, so
// we can just read directly.
while (resid > 0 && (r = (*fp->_read)(fp->_cookie, p, resid)) > 0) {
p += r;
resid -= r;
}
FUNLOCKFILE(fp);
return ((total - resid) / size);
}
// END android-added
while (resid > (size_t)(r = fp->_r)) {
(void)memcpy((void *)p, (void *)fp->_p, (size_t)r);
fp->_p += r;
/* fp->_r = 0 ... done in __srefill */