Clear up input file code in purr.

In order to accept a file from stdin, it is necessary to buffer it in
its entirety, so that the final size is known and can be included in the
HTTP header.

As it stands, the stream mode for mmap_file, when used for reading
files, is not extremely useful.

Also:

- files.c: look at fwrite error.
- mmap_file.c: disable buffering for FILE stream.

files.c

@@ -185,7 +185,7 @@ size_t mmap_to_ssl(struct transmission_information ti)
         if (ti.ssl) {
             err = br_sslio_write_all(ti.ioc, tmp, wlen);
         } else {
-            fwrite(tmp, 1, wlen, ti.socket_write_stream);
+            err = (int)fwrite(tmp, 1, wlen, ti.socket_write_stream) != wlen;
         }
         if (err == 0) {
             rv += wlen;

mmap_file.c

@@ -54,6 +54,9 @@ struct mmap_file create_mmap_from_FILE(FILE *stream, const char *mode)
         return rv;
     }
 
+    // remove buffering
+    setbuf(stream, NULL);
+
     rv.stream = stream;
     rv.use_stream = true;
     // make data pointer valid, for error checking
@@ -116,7 +119,6 @@ int read_from_mmap(struct mmap_file *file, uint8_t *buffer, int n)
     assert(file->prot & PROT_READ);
 
     if (file->use_stream) {
-        // TODO: returns bogus values, transmissions end up empty
         return fread(buffer, 1, n, file->stream);
     }
 

purr.c

@@ -188,19 +188,28 @@ int main (int argc, char **argv)
         }
         url = argv[1];
     } else if (send) {
-        if (argc == 2 && strcmp(argv[1], "-")) {
-            input = create_mmap_from_file(argv[1], PROT_READ);
-            if (ERROR_MMAP(input)) {
-                perror("couln't open input file");
-                exit(EXIT_FAILURE);
-            }
-        } else if (argc > 2) {
+        bool using_stdin = false;
+        if (argc > 2) {
             usage(true);
+        } else if (argc == 2 && strcmp(argv[1], "-")) {
+            input = create_mmap_from_file(argv[1], PROT_READ);
         } else {
-            fputs("stdin not supported for ~now~ meow!\n", stderr);
+            // it is necessary to read from stdin instead of streaming a file,
+            // because the HTTP header includes a Content-Length field,
+            // which needs to be populated.
+            input = create_mmap_from_file(NULL, PROT_MEM);
+            using_stdin = true;
+        }
+
+        if (ERROR_MMAP(input)) {
+            perror("create_mmap_from_file()");
             exit(EXIT_FAILURE);
         }
 
+        if (using_stdin) {
+            input.size = fread(input.data, 1, OUTPUT_FILE_SIZE, stdin);
+        }
+
         if (url_opt) {
             url = url_opt;
         } else {