Fix #89: User-specific tmp file for copying filenames

Use distinct (by username) tmp filename to copy file paths.

The pattern used is:
/tmp/nnncp$USER

If username is 'arun', the file name is `/tmp/nnncparun`.

README.md

@@ -385,7 +385,7 @@ This is particularly useful if you are planning to copy the whole string to the
 
 #### copy file paths when X is missing
 
-A very common scenario on headless remote servers connected via SSH. As the clipboard is missing, `nnn` copies the path names to the tmp file `/tmp/nnncp`.
+A very common scenario on headless remote servers connected via SSH. As the clipboard is missing, `nnn` copies the path names to the tmp file `/tmp/nnncp$USER`.
 
 `nnn` needs to know X is unavailable:
 
@@ -394,15 +394,15 @@ A very common scenario on headless remote servers connected via SSH. As the clip
 Use <kbd>^Y</kbd> and/or <kbd>^K</kbd> to copy file paths as usual. To use the copied paths from the cmdline, use command substitution:
 
     # bash/zsh
-    ls -ltr `cat /tmp/nnncp`
-    ls -ltr $(cat /tmp/nnncp)
+    ls -ltr `cat /tmp/nnncpuser`
+    ls -ltr $(cat /tmp/nnncpuser)
 
     # fish
-    ls -ltr (cat /tmp/nnncp)
+    ls -ltr (cat /tmp/nnncpuser)
 
 An alias may be handy:
 
-    alias ncp='cat /tmp/nnncp'
+    alias ncp='cat /tmp/nnncpuser'
 
 so you can -
 

nnn.1

@@ -248,7 +248,7 @@ screensaver.
     -------------------------------------
 .Ed
 .Pp
-\fBNNN_NO_X:\fR X display is unavailable. Copy file path(s) to \fI/tmp/nnncp\fR.
+\fBNNN_NO_X:\fR X display is unavailable. Copy file path(s) to \fI/tmp/nnncp$USER\fR.
 .Bd -literal
     export NNN_NO_X=1
 .Ed

nnn.c

@@ -195,9 +195,6 @@ disabledbg()
 #define NUM_EVENT_FDS 1
 #endif
 
-/* File path to copy file names when X is not available */
-#define TMP_CP_PATH "/tmp/nnncp"
-
 /* TYPE DEFINITIONS */
 typedef unsigned long ulong;
 typedef unsigned int uint;
@@ -317,6 +314,9 @@ static const char messages[][16] =
 /* For use in functions which are isolated and don't return the buffer */
 static char g_buf[MAX_CMD_LEN] __attribute__ ((aligned));
 
+/* Buffer for file path copy file */
+static char g_cppath[48] __attribute__ ((aligned));
+
 /* Forward declarations */
 static void redraw(char *path);
 
@@ -635,7 +635,7 @@ xbasename(char *path)
 static void
 writecp(const char *buf, const size_t buflen)
 {
-	FILE *fp = fopen(TMP_CP_PATH, "w");
+	FILE *fp = fopen(g_cppath, "w");
 
 	if (fp) {
 		fwrite(buf, 1, buflen, fp);
@@ -3318,9 +3318,14 @@ main(int argc, char *argv[])
 		cfg.quote = 1;
 
 	/* Check if X11 is available */
-	if (getenv("NNN_NO_X"))
+	if (getenv("NNN_NO_X")) {
 		cfg.noxdisplay = 1;
 
+		struct passwd *pass = getpwuid(getuid());
+		xstrlcpy(g_cppath, "/tmp/nnncp", 11);
+		xstrlcpy(g_cppath + 10, pass->pw_name, 33);
+	}
+
 	signal(SIGINT, SIG_IGN);
 
 	/* Test initial path */