io: allow slurping files with a given size

[libjh.git] / io.c

diff --git a/io.c b/io.c
index 6c70b97..3c0a8eb 100644 (file)
--- a/io.c
+++ b/io.c
@@ -67,7 +67,10 @@ PUBLIC_FN ssize_t write_nointr(int fd, void *buf, size_t count, int *last_res) {
 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_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) {
+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
   int errno_;
   
   // Let's just guess that the file is 1023 bytes. Will become 1024 with


@@ -75,6 +78,13 @@ 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? */
   
   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
   int padlen = (flags&JH_SLURP_8BYTE_PAD)?8:1;
   
   // If we can determine the exact size, we don't have to guess. So try


@@ -113,6 +123,12 @@ PUBLIC_FN char *slurp_fd(int fd, size_t *len_out, int flags) {
         char *buf_ = realloc(buf, done+padlen);
         if (buf_) buf = buf_;
       }
         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;
     }
       if (len_out) *len_out = done;
       return buf;
     }


@@ -120,7 +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);
   int fd = open(path, O_RDONLY|O_CLOEXEC);
   if (fd == -1) return NULL;
   char *res = slurp_fd(fd, len_out, flags);


@@ -132,10 +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).
 
 // 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);
   
   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;
   if (fd == -1) return 1;
   ssize_t write_res = write_nointr(fd, buf, len, NULL);
   int write_errno = errno;