slurp_fd: add flag for creating 8-nullbytes-padded buffers

diff --git a/io.c b/io.c
index a7696f9..6c70b97 100644 (file)
--- a/io.c
+++ b/io.c
@@ -66,6 +66,7 @@ PUBLIC_FN ssize_t write_nointr(int fd, void *buf, size_t count, int *last_res) {
 // this and can specify len_out as NULL.
 PUBLIC_CONST JH_SLURP_NO_STAT 1
 PUBLIC_CONST JH_SLURP_REALLOC 2 /* realloc result block if it saves RAM */
+PUBLIC_CONST JH_SLURP_8BYTE_PAD 4 /* pad buffer with eight nullbytes, not one */
 PUBLIC_FN char *slurp_fd(int fd, size_t *len_out, int flags) {
   int errno_;
   
@@ -74,6 +75,8 @@ PUBLIC_FN char *slurp_fd(int fd, size_t *len_out, int flags) {
   size_t size_guess = 1023;
   bool trusted_guess = false; /* can we rely on the guess? */
   
+  int padlen = (flags&JH_SLURP_8BYTE_PAD)?8:1;
+  
   // If we can determine the exact size, we don't have to guess. So try
   // to determine the exact size.
   if (!(flags&JH_SLURP_NO_STAT)) {
@@ -90,7 +93,7 @@ PUBLIC_FN char *slurp_fd(int fd, size_t *len_out, int flags) {
   int done = 0;
   
   while (1) {
-    buf = realloc(buf, size_guess+1);
+    buf = realloc(buf, size_guess+padlen);
     if (buf == NULL) return NULL;
     int last_res;
     ssize_t read_res = read_nointr(fd, buf+done, size_guess-done, &last_res);
@@ -98,12 +101,16 @@ PUBLIC_FN char *slurp_fd(int fd, size_t *len_out, int flags) {
     done += read_res;
     if (last_res == 0 || trusted_guess) {
       // out
-      buf[done] = '\0';
+      if (padlen == 1) {
+        buf[done] = '\0';
+      } else {
+        *(uint64_t*)(buf+done) = 0;
+      }
       if (done != size_guess && (flags&JH_SLURP_REALLOC)) {
         // Well, it'd be weird if shrinking could fail... but meh, I can't find
         // an explicit statement about this being disallowed, so try staying on
         // the safe side.
-        char *buf_ = realloc(buf, done+1);
+        char *buf_ = realloc(buf, done+padlen);
         if (buf_) buf = buf_;
       }
       if (len_out) *len_out = done;