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-rw-r--r--wrapper.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/wrapper.c b/wrapper.c
index 0cc5636..bc1bfb8 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -174,6 +174,24 @@ ssize_t xwrite(int fd, const void *buf, size_t len)
}
}
+/*
+ * xpread() is the same as pread(), but it automatically restarts pread()
+ * operations with a recoverable error (EAGAIN and EINTR). xpread() DOES
+ * NOT GUARANTEE that "len" bytes is read even if the data is available.
+ */
+ssize_t xpread(int fd, void *buf, size_t len, off_t offset)
+{
+ ssize_t nr;
+ if (len > MAX_IO_SIZE)
+ len = MAX_IO_SIZE;
+ while (1) {
+ nr = pread(fd, buf, len, offset);
+ if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
+ continue;
+ return nr;
+ }
+}
+
ssize_t read_in_full(int fd, void *buf, size_t count)
{
char *p = buf;
@@ -214,6 +232,26 @@ ssize_t write_in_full(int fd, const void *buf, size_t count)
return total;
}
+ssize_t pread_in_full(int fd, void *buf, size_t count, off_t offset)
+{
+ char *p = buf;
+ ssize_t total = 0;
+
+ while (count > 0) {
+ ssize_t loaded = xpread(fd, p, count, offset);
+ if (loaded < 0)
+ return -1;
+ if (loaded == 0)
+ return total;
+ count -= loaded;
+ p += loaded;
+ total += loaded;
+ offset += loaded;
+ }
+
+ return total;
+}
+
int xdup(int fd)
{
int ret = dup(fd);