Cleaup read() and write() variants, plus a couple of new functions like

xlseek and fdlength() for the new mkswap.

1 files changed, 69 insertions, 16 deletions

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index d843414f9..8562a4fcb 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -120,40 +120,55 @@ int bb_xopen3(const char *pathname, int flags, int mode)
 #endif
 
 #ifdef L_xread
-ssize_t bb_xread(int fd, void *buf, size_t count)
+
+// Die with an error message if we can't read the entire buffer.
+
+void xread(int fd, void *buf, size_t count)
 {
-        ssize_t size;
+        while (count) {
+                ssize_t size;
 
-        size = read(fd, buf, count);
-        if (size < 0) {
-                bb_perror_msg_and_die(bb_msg_read_error);
+                if ((size = safe_read(fd, buf, count)) < 1)
+                        bb_error_msg_and_die("Short read");
+                count -= size;
+                buf = ((char *) buf) + size;
         }
-        return(size);
 }
 #endif
 
-#ifdef L_xread_all
-void bb_xread_all(int fd, void *buf, size_t count)
-{
-        ssize_t size;
+#ifdef L_xwrite
 
+// Die with an error message if we can't write the entire buffer.
+
+void xwrite(int fd, void *buf, size_t count)
+{
         while (count) {
-                if ((size = bb_xread(fd, buf, count)) == 0) {   /* EOF */
-                        bb_error_msg_and_die("Short read");
-                }
+                ssize_t size;
+
+                if ((size = safe_write(fd, buf, count)) < 1)
+                        bb_error_msg_and_die("Short write");
                 count -= size;
                 buf = ((char *) buf) + size;
         }
-        return;
+}
+#endif
+
+#ifdef L_xlseek
+
+// Die if we can't lseek to the right spot.
+
+void xlseek(int fd, off_t offset, int whence)
+{
+        if (whence != lseek(fd, offset, whence)) bb_error_msg_and_die("lseek");
 }
 #endif
 
 #ifdef L_xread_char
-unsigned char bb_xread_char(int fd)
+unsigned char xread_char(int fd)
 {
         char tmp;
 
-        bb_xread_all(fd, &tmp, 1);
+        xread(fd, &tmp, 1);
 
         return(tmp);
 }
@@ -294,3 +309,41 @@ void xsetuid(uid_t uid)
         if (setuid(uid)) bb_error_msg_and_die("setuid");
 }
 #endif
+
+#ifdef L_fdlength
+off_t fdlength(int fd)
+{
+        off_t bottom = 0, top = 0, pos;
+        long size;
+
+        // If the ioctl works for this, return it.
+
+        if (ioctl(fd, BLKGETSIZE, &size) >= 0) return size*512;
+
+        // If not, do a binary search for the last location we can read.
+
+        do {
+                char temp;
+
+                pos = bottom + (top - bottom) / 2;;
+
+                // If we can read from the current location, it's bigger.
+
+                if (lseek(fd, pos, 0)>=0 && safe_read(fd, &temp, 1)==1) {
+                        if (bottom == top) bottom = top = (top+1) * 2;
+                        else bottom = pos;
+
+                // If we can't, it's smaller.
+
+                } else {
+                        if (bottom == top) {
+                                if (!top) return 0;
+                                bottom = top/2;
+                        }
+                        else top = pos;
+                }
+        } while (bottom + 1 != top);
+
+        return pos + 1;
+}
+#endif