Make read_file() thread-safe.

This is long overdue, of course; I knew this function was a quick hack,
but didn't realize it was a problem until Christophe Thommeret reported
an issue that looked a lot like this.

diff --git a/util.cpp b/util.cpp
index e08a0859a25ef09ae7ddba9945ef648b26934260..3ebf162d31a0558ddfb54d3a8520706035ee45e6 100644 (file)
--- a/util.cpp
+++ b/util.cpp
@@ -87,17 +87,41 @@ string read_file(const string &filename)
 {
        const string full_pathname = *movit_data_directory + "/" + filename;
 
-       static char buf[131072];
        FILE *fp = fopen(full_pathname.c_str(), "r");
        if (fp == NULL) {
                perror(full_pathname.c_str());
                exit(1);
        }
 
-       int len = fread(buf, 1, sizeof(buf), fp);
+       int ret = fseek(fp, 0, SEEK_END);
+       if (ret == -1) {
+               perror("fseek(SEEK_END)");
+               exit(1);
+       }
+
+       int size = ftell(fp);
+
+       ret = fseek(fp, 0, SEEK_SET);
+       if (ret == -1) {
+               perror("fseek(SEEK_SET)");
+               exit(1);
+       }
+
+       string str;
+       str.resize(size);
+       ret = fread(&str[0], size, 1, fp);
+       if (ret == -1) {
+               perror("fread");
+               exit(1);
+       }
+       if (ret == 0) {
+               fprintf(stderr, "Short read when trying to read %d bytes from %s\n",
+                       size, full_pathname.c_str());
+               exit(1);
+       }
        fclose(fp);
 
-       return string(buf, len);
+       return str;
 }
 
 string read_version_dependent_file(const string &base, const string &extension)