| Message ID | 1290619139-5634-1-git-send-email-mohan@in.ibm.com |
|---|---|
| State | New |
| Headers | show |
On Wed, Nov 24, 2010 at 5:18 PM, M. Mohan Kumar <mohan@in.ibm.com> wrote: > Add qemu_read_full function > > Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com> > --- > osdep.c | 29 +++++++++++++++++++++++++++++ > qemu-common.h | 2 ++ > 2 files changed, 31 insertions(+), 0 deletions(-) > > diff --git a/osdep.c b/osdep.c > index 327583b..7046b32 100644 > --- a/osdep.c > +++ b/osdep.c > @@ -127,6 +127,35 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count) > } > > /* > + * A variant of read(2) which handles interrupted read. > + * Simlar to qemu_write_full function > + * > + * Return the number of bytes read. > + * > + */ Two points worth noting in the comment (stolen from qemu_write_full): 1. "This function don't work with non-blocking fd's." 2. "Set errno if fewer than `count' bytes are read." Normal QEMU style would be to return -errno, so it's important to point out this exception to the rule. > +ssize_t qemu_read_full(int fd, void *buf, size_t count) > +{ > + ssize_t ret = 0; > + ssize_t total = 0; > + > + while (count) { > + ret = read(fd, buf, count); > + if (ret < 0) { > + if (errno == EINTR) { > + continue; > + } > + break; > + } > + > + count -= ret; > + buf += ret; > + total += ret; > + } > + > + return total; > +} On EOF read(2) will return 0. Right now we don't handle this case and go into an infinite loop. Stefan
diff --git a/osdep.c b/osdep.c index 327583b..7046b32 100644 --- a/osdep.c +++ b/osdep.c @@ -127,6 +127,35 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count) } /* + * A variant of read(2) which handles interrupted read. + * Simlar to qemu_write_full function + * + * Return the number of bytes read. + * + */ +ssize_t qemu_read_full(int fd, void *buf, size_t count) +{ + ssize_t ret = 0; + ssize_t total = 0; + + while (count) { + ret = read(fd, buf, count); + if (ret < 0) { + if (errno == EINTR) { + continue; + } + break; + } + + count -= ret; + buf += ret; + total += ret; + } + + return total; +} + +/* * Opens a socket with FD_CLOEXEC set */ int qemu_socket(int domain, int type, int protocol) diff --git a/qemu-common.h b/qemu-common.h index b3957f1..0f60e08 100644 --- a/qemu-common.h +++ b/qemu-common.h @@ -190,6 +190,8 @@ void qemu_mutex_unlock_iothread(void); int qemu_open(const char *name, int flags, ...); ssize_t qemu_write_full(int fd, const void *buf, size_t count) QEMU_WARN_UNUSED_RESULT; +ssize_t qemu_read_full(int fd, void *buf, size_t count) + QEMU_WARN_UNUSED_RESULT; void qemu_set_cloexec(int fd); #ifndef _WIN32
Add qemu_read_full function Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com> --- osdep.c | 29 +++++++++++++++++++++++++++++ qemu-common.h | 2 ++ 2 files changed, 31 insertions(+), 0 deletions(-)