From e9fb7a67dacc67ef0b9debe1c897e9c2d60b2c3c Mon Sep 17 00:00:00 2001
From: Michael Jumper <mike.jumper@guac-dev.org>
Date: Wed, 27 Jan 2016 11:50:56 -0800
Subject: [PATCH] GUAC-1452: Try and retry the specified filename until success
 or no further possibilities exist.

---
 src/terminal/typescript.c | 84 +++++++++++++++++++++++++++++++++++----
 src/terminal/typescript.h | 19 +++++++++
 2 files changed, 95 insertions(+), 8 deletions(-)

diff --git a/src/terminal/typescript.c b/src/terminal/typescript.c
index 2460cadb..9127d785 100644
--- a/src/terminal/typescript.c
+++ b/src/terminal/typescript.c
@@ -26,6 +26,7 @@
 
 #include <guacamole/timestamp.h>
 
+#include <errno.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -34,21 +35,88 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 
+/**
+ * Attempts to open a new typescript data file within the given path and having
+ * the given name. If such a file already exists, sequential numeric suffixes
+ * (.1, .2, .3, etc.) are appended until a filename is found which does not
+ * exist (or until the maximum number of numeric suffixes has been tried). If
+ * the file absolutely cannot be opened due to an error, -1 is returned and
+ * errno is set appropriately.
+ *
+ * @param path
+ *     The full path to the directory in which the data file should be created.
+ *
+ * @param name
+ *     The name of the data file which should be crated within the given path.
+ *
+ * @param basename
+ *     A buffer in which the path, a path separator, the filename, any
+ *     necessary suffix, and a NULL terminator will be stored. If insufficient
+ *     space is available, -1 will be returned, and errno will be set to
+ *     ENAMETOOLONG.
+ *
+ * @param basename_size
+ *     The number of bytes available within the provided basename buffer.
+ *
+ * @return
+ *     The file descriptor of the open data file if open succeeded, or -1 on
+ *     failure.
+ */
+static int guac_terminal_typescript_open_data_file(const char* path,
+        const char* name, char* basename, int basename_size) {
+
+    int i;
+
+    /* Concatenate path and name (separated by a single slash) */
+    int basename_length = snprintf(basename,
+            basename_size - GUAC_TERMINAL_TYPESCRIPT_MAX_SUFFIX_LENGTH ,
+            "%s/%s", path, name);
+
+    /* Abort if maximum length reached */
+    if (basename_length ==
+            basename_size - GUAC_TERMINAL_TYPESCRIPT_MAX_SUFFIX_LENGTH) {
+        errno = ENAMETOOLONG;
+        return -1;
+    }
+
+    /* Attempt to open typescript data file */
+    int data_fd = open(basename,
+            O_CREAT | O_EXCL | O_WRONLY,
+            S_IRUSR | S_IWUSR);
+
+    /* Prepare basename for additional suffix */
+    basename[basename_length] = '.';
+    char* suffix = basename + basename_length + 1;
+
+    /* Continue retrying alternative suffixes if file already exists */
+    for (i = 1; data_fd == -1 && errno == EEXIST
+            && i <= GUAC_TERMINAL_TYPESCRIPT_MAX_SUFFIX; i++) {
+
+        /* Append new suffix */
+        sprintf(suffix, "%i", i);
+
+        /* Retry with newly-suffixed filename */
+        data_fd = open(basename,
+                O_CREAT | O_EXCL | O_WRONLY,
+                S_IRUSR | S_IWUSR);
+
+    }
+
+    return data_fd;
+
+}
+
 guac_terminal_typescript* guac_terminal_typescript_alloc(const char* path,
         const char* name, int create_path) {
 
+    char basename[GUAC_TERMINAL_TYPESCRIPT_MAX_NAME_LENGTH];
+
     guac_terminal_typescript* typescript;
     int data_fd, timing_fd;
 
-    /* TODO: Determing data and timing filenames prior to open() calls.
-     * Be sure not to use open() itself to test for existence, as that could
-     * result in tons of typescript data files being unnecessarily created.
-     */
-
     /* Attempt to open typescript data file */
-    data_fd = open("/tmp/typescript-data",
-            O_CREAT | O_EXCL | O_WRONLY,
-            S_IRUSR | S_IWUSR);
+    data_fd = guac_terminal_typescript_open_data_file(path, name,
+            basename, sizeof(basename));
     if (data_fd == -1)
         return NULL;
 
diff --git a/src/terminal/typescript.h b/src/terminal/typescript.h
index b6bba80f..52f2f69d 100644
--- a/src/terminal/typescript.h
+++ b/src/terminal/typescript.h
@@ -47,6 +47,25 @@
  */
 #define GUAC_TERMINAL_TYPESCRIPT_MAX_DELAY 86400000
 
+/**
+ * The maximum numeric value allowed for the .1, .2, .3, etc. suffix appended
+ * to the end of the typescript filename if a typescript having the requested
+ * name already exists.
+ */
+#define GUAC_TERMINAL_TYPESCRIPT_MAX_SUFFIX 255
+
+/**
+ * The maximum length of the string containing a sequential numeric suffix
+ * between 1 and GUAC_TERMINAL_TYPESCRIPT_MAX_SUFFIX inclusive, in bytes.
+ */
+#define GUAC_TERMINAL_TYPESCRIPT_MAX_SUFFIX_LENGTH 4
+
+/**
+ * The maximum overall length of the full path to the typescript file,
+ * including any additional suffix, in bytes.
+ */
+#define GUAC_TERMINAL_TYPESCRIPT_MAX_NAME_LENGTH 2048
+
 /**
  * An active typescript, consisting of a data file (raw terminal output) and
  * timing file (related timestamps and byte counts).