string: add TPRINTF macro for constructing temporary small strings

[libjh.git] / io.c

diff --git a/io.c b/io.c
index a7696f9..3c0a8eb 100644 (file)
--- a/io.c
+++ b/io.c
@@ -66,7 +66,11 @@ 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_FN char *slurp_fd(int fd, size_t *len_out, int flags) {
+PUBLIC_CONST JH_SLURP_8BYTE_PAD 4 /* pad buffer with eight nullbytes, not one */
+PUBLIC_CONST JH_SLURP_FIXSIZE 8 /* len_out is actually input and specifies
+HEADER                             the expected length. if there is more data,
+HEADER                             that might be ignored silently. */
+PUBLIC_FN void *slurp_fd(int fd, size_t *len_out, int flags) {
   int errno_;
   
   // Let's just guess that the file is 1023 bytes. Will become 1024 with
@@ -74,6 +78,15 @@ 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? */
   
+  if (flags&JH_SLURP_FIXSIZE) {
+    size_guess = *len_out;
+    trusted_guess = true;
+    // if we want a fixed size, of course we don't want to stat
+    flags |= JH_SLURP_NO_STAT;
+  }
+  
+  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 +103,7 @@ 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);
@@ -98,14 +111,24 @@ 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 (done != size_guess && (flags&JH_SLURP_FIXSIZE)) {
+        free(buf);
+        // not the most correct error message ever, but whatever.
+        errno = EFBIG;
+        return NULL;
+      }
       if (len_out) *len_out = done;
       return buf;
     }
@@ -113,7 +136,7 @@ PUBLIC_FN char *slurp_fd(int fd, size_t *len_out, int flags) {
   }
 }
 
-PUBLIC_FN char *slurp_file(char *path, size_t *len_out, int flags) {
+PUBLIC_FN void *slurp_file(char *path, size_t *len_out, int flags) {
   int fd = open(path, O_RDONLY|O_CLOEXEC);
   if (fd == -1) return NULL;
   char *res = slurp_fd(fd, len_out, flags);
@@ -125,10 +148,10 @@ PUBLIC_FN char *slurp_file(char *path, size_t *len_out, int flags) {
 
 // Write data into a file. len can be -1; that means that
 // the real length is strlen(buf).
-PUBLIC_FN int write_file(char *path, char *buf, ssize_t len, int open_flags) {
+PUBLIC_FN int write_file(char *path, void *buf, ssize_t len, int open_flags) {
   if (len == -1) len = strlen(buf);
   
-  int fd = open(path, open_flags|O_CLOEXEC, 0777);
+  int fd = open(path, open_flags|O_CLOEXEC|O_WRONLY, 0777);
   if (fd == -1) return 1;
   ssize_t write_res = write_nointr(fd, buf, len, NULL);
   int write_errno = errno;