Initial revision

1 files changed, 99 insertions, 0 deletions

diff --git a/zwgc/file.c b/zwgc/file.c
new file mode 100644
index 0000000..a46a4f5
--- /dev/null
+++ b/zwgc/file.c
@@ -0,0 +1,99 @@
+#include <errno.h>
+#include <sys/types.h>
+#include <stdio.h>
+#include <pwd.h>
+#include "new_memory.h"
+#include "new_string.h"
+#include "error.h"
+
+/*
+ *    char *get_home_directory()
+ *
+ *        Effects: Attempts to locate the user's (by user, the owner of this
+ *                 process is meant) home directory & return its pathname.
+ *                 Returns NULL if unable to do so.  Does so by first checking
+ *                 the environment variable HOME.  If it is unset, falls back
+ *                 on the user's password entry.
+ *         Note: The returned pointer may point to a static buffer & hence
+ *               go away on further calls to getenv, get_home_directory,
+ *               getpwuid, or related calls.  The caller should copy it
+ *               if necessary.
+ */
+
+char *get_home_directory()
+{
+    char *result;
+    char *getenv();
+    struct passwd *passwd_entry;
+
+    if (result = getenv("HOME"))
+      return(result);
+
+    if (!(passwd_entry = getpwuid(getuid())))
+      return(NULL);
+
+    return(passwd_entry->pw_dir);
+}
+
+/*
+ *
+ */
+
+FILE *locate_file(override_filename, home_dir_filename, fallback_filename)
+     char *override_filename;
+     char *home_dir_filename;
+     char *fallback_filename;
+{
+    char *filename;
+    FILE *result;
+
+    errno = 0;
+
+    if (override_filename) {
+	if (string_Eq(override_filename, "-"))
+	  return(stdin);
+	
+	result = fopen(override_filename, "r");
+	if (!(result = fopen(override_filename, "r"))) {
+	    /* <<<>>> */
+	    fprintf(stderr, "zwgc: error while opening %s for reading: ",
+		   override_filename);
+	    perror("");
+	}
+	return(result);
+    }
+
+    if (home_dir_filename) {
+	if (filename = get_home_directory()) {
+	    filename = string_Concat(filename, "/");
+	    filename = string_Concat2(filename, home_dir_filename);
+	    result = fopen(filename, "r");
+	    if (result) {
+		free(filename);
+		return(result);
+	    }
+	    if (errno != ENOENT) {
+		/* <<<>>> */
+		fprintf(stderr, "zwgc: error while opening %s for reading: ",
+			filename);
+		perror("");
+		free(filename);
+		return(result);
+	    }
+	    free(filename);
+	} else
+	  ERROR("unable to find your home directory.\n");
+    }
+
+    if (fallback_filename) {
+	if (!(result = fopen(fallback_filename, "r"))) {
+	    /* <<<>>> */
+	    fprintf(stderr, "zwgc: error while opening %s for reading: ",
+		   fallback_filename);
+	    perror("");
+	}
+	return(result);
+    }
+
+    return(NULL);
+}