1 files changed, 71 insertions, 0 deletions
diff --git a/hw4/cgiprog/file_reader.c b/hw4/cgiprog/file_reader.c
new file mode 100644
index 0000000..dec8b30
--- /dev/null
+++ b/hw4/cgiprog/file_reader.c
@@ -0,0 +1,71 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define NL "\015\012"
+
+int main (int argc, char* argv[]) {
+	char* qs = getenv ("QUERY_STRING");
+	if (qs == NULL || *qs == '\0') {
+		fputs (
+			"HTTP/1.1 400 Bad Request" NL
+			"Content-Type: text/html" NL NL
+			"<html><head><title>400 Bad Request</title></head>" NL
+			"<body><p>Query string is missing</p>"
+			"</body></html>" NL, stdout);
+		return 1;
+	}
+
+	if (strncmp (qs, "filename=", 9)) {
+		fputs (
+			"HTTP/1.1 400 Bad Request" NL
+			"Content-Type: text/html" NL NL
+			"<html><head><title>400 Bad Request</title></head>" NL
+			"<body><p>Query string is not valid</p>"
+			"</body></html>" NL, stdout);
+		return 1;
+	}
+
+	char* fn = qs + 9;
+	int fd = open (fn, O_RDONLY);
+	if (fd < 0) {
+		switch (errno) {
+			case ENOENT:
+				printf (
+					"HTTP/1.1 404 Not Found" NL
+					"Content-Type: text/html" NL NL
+					"<html><head><title>404 Not Found</title></head>" NL
+					"<body><p>File `%s\' cannot be found on the system</p>" NL
+					"</body></html>" NL, fn);
+				return 2;
+			case EACCES:
+				printf (
+					"HTTP/1.1 403 Forbidden" NL
+					"Content-Type: text/html" NL NL
+					"<html><head><title>403 Forbidden</title></head>" NL
+					"<body><p>Access to `%s\' is denied</p>" NL
+					"</body></html>" NL, fn);
+				return 3;
+			default:
+				printf (
+					"HTTP/1.1 500 Internal Server Error" NL
+					"Content-Type: text/html" NL NL
+					"<html><head><title>500 Internal Server Error</title></head>" NL
+					"<body><p>%s</p>" NL
+					"</body></html>" NL, strerror (errno));
+				return 4;
+		}
+	}
+
+	fputs ("Content-Type: application/octet-stream" NL NL, stdout);
+	fflush (stdout);
+
+	char buf[4096];
+	ssize_t r;
+	for (; (r = read (fd, buf, 4096)) > 0; write (1, buf, r));
+
+	return 0;
+}