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Ensure short read(2)s/write(2)s are properly handled by IO utilities

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`read(2)` and `write(2)` may read or write fewer bytes than were
requested. In order to robustly ensure that all of the requested bytes
are read/written, these edge-cases must be handled.
This commit is contained in:
Kevin Svetlitski 2023-08-10 10:43:42 -07:00 committed by Qi Wang
parent 254c4847e8
commit d2c9ed3d1e
1 changed files with 33 additions and 2 deletions
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35
include/jemalloc/internal/malloc_io.h
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@ -68,7 +68,7 @@ void malloc_cprintf(write_cb_t *write_cb, void *cbopaque, const char *format,
void malloc_printf(const char *format, ...) JEMALLOC_FORMAT_PRINTF(1, 2);
static inline ssize_t
malloc_write_fd(int fd, const void *buf, size_t count) {
malloc_write_fd_syscall(int fd, const void *buf, size_t count) {
#if defined(JEMALLOC_USE_SYSCALL) && defined(SYS_write)
/*
* Use syscall(2) rather than write(2) when possible in order to avoid
@ -90,7 +90,22 @@ malloc_write_fd(int fd, const void *buf, size_t count) {
}
static inline ssize_t
malloc_read_fd(int fd, void *buf, size_t count) {
malloc_write_fd(int fd, const void *buf, size_t count) {
size_t bytes_written = 0;
do {
ssize_t result = malloc_write_fd_syscall(fd,
&((const byte_t *)buf)[bytes_written],
count - bytes_written);
if (result < 0) {
return result;
}
bytes_written += result;
} while (bytes_written < count);
return bytes_written;
}
static inline ssize_t
malloc_read_fd_syscall(int fd, void *buf, size_t count) {
#if defined(JEMALLOC_USE_SYSCALL) && defined(SYS_read)
long result = syscall(SYS_read, fd, buf, count);
#else
@ -103,4 +118,20 @@ malloc_read_fd(int fd, void *buf, size_t count) {
return (ssize_t)result;
}
static inline ssize_t
malloc_read_fd(int fd, void *buf, size_t count) {
size_t bytes_read = 0;
do {
ssize_t result = malloc_read_fd_syscall(fd,
&((byte_t *)buf)[bytes_read], count - bytes_read);
if (result < 0) {
return result;
} else if (result == 0) {
break;
}
bytes_read += result;
} while (bytes_read < count);
return bytes_read;
}
#endif /* JEMALLOC_INTERNAL_MALLOC_IO_H */