Fix sparse warnings and add an extra sprinkling of const.

This is more or less the equivalent of Sven-Haegar Koch's fixes in the 1.1
branch.

lib/pidfile.c

@@ -27,6 +27,8 @@
 
 #include "system.h"
 
+#include "pidfile.h"
+
 #ifndef HAVE_MINGW
 /* read_pid
  *
@@ -34,7 +36,7 @@
  * 0 is returned if either there's no pidfile, it's empty
  * or no pid can be read.
  */
-pid_t read_pid (char *pidfile)
+pid_t read_pid (const char *pidfile)
 {
   FILE *f;
   long pid;
@@ -53,7 +55,7 @@ pid_t read_pid (char *pidfile)
  * table (using /proc) to determine if the process already exists. If
  * so the pid is returned, otherwise 0.
  */
-pid_t check_pid (char *pidfile)
+pid_t check_pid (const char *pidfile)
 {
   pid_t pid = read_pid(pidfile);
 
@@ -79,7 +81,7 @@ pid_t check_pid (char *pidfile)
  * Writes the pid to the specified file. If that fails 0 is
  * returned, otherwise the pid.
  */
-pid_t write_pid (char *pidfile)
+pid_t write_pid (const char *pidfile)
 {
   FILE *f;
   int fd;
@@ -124,7 +126,7 @@ pid_t write_pid (char *pidfile)
  * Remove the the specified file. The result from unlink(2)
  * is returned
  */
-int remove_pid (char *pidfile)
+int remove_pid (const char *pidfile)
 {
   return unlink (pidfile);
 }

lib/pidfile.h

@@ -26,7 +26,7 @@
  * 0 is returned if either there's no pidfile, it's empty
  * or no pid can be read.
  */
-pid_t read_pid (char *pidfile);
+extern pid_t read_pid (const char *pidfile);
 
 /* check_pid
  *
@@ -34,19 +34,19 @@ pid_t read_pid (char *pidfile);
  * table (using /proc) to determine if the process already exists. If
  * so 1 is returned, otherwise 0.
  */
-pid_t check_pid (char *pidfile);
+extern pid_t check_pid (const char *pidfile);
 
 /* write_pid
  *
  * Writes the pid to the specified file. If that fails 0 is
  * returned, otherwise the pid.
  */
-pid_t write_pid (char *pidfile);
+extern pid_t write_pid (const char *pidfile);
 
 /* remove_pid
  *
  * Remove the the specified file. The result from unlink(2)
  * is returned
  */
-int remove_pid (char *pidfile);
+extern int remove_pid (const char *pidfile);
 #endif

lib/utils.c

@@ -23,9 +23,9 @@
 #include "../src/logger.h"
 #include "utils.h"
 
-const char hexadecimals[] = "0123456789ABCDEF";
+static const char hexadecimals[] = "0123456789ABCDEF";
 
-int charhex2bin(char c) {
+static int charhex2bin(char c) {
 	if(isdigit(c))
 		return c - '0';
 	else
@@ -67,7 +67,7 @@ const char *winerror(int err) {
 }
 #endif
 
-unsigned int bitfield_to_int(void *bitfield, size_t size) {
+unsigned int bitfield_to_int(const void *bitfield, size_t size) {
 	unsigned int value = 0;
 	if(size > sizeof value)
 		size = sizeof value;

lib/utils.h

@@ -40,6 +40,6 @@ extern const char *winerror(int);
 #define sockinprogress(x) ((x) == EINPROGRESS)
 #endif
 
-extern unsigned int bitfield_to_int(void *bitfield, size_t size);
+extern unsigned int bitfield_to_int(const void *bitfield, size_t size);
 
 #endif							/* __TINC_UTILS_H__ */

lib/xalloc.h

@@ -16,7 +16,7 @@ extern int xalloc_exit_failure;
 extern char *const xalloc_msg_memory_exhausted;
 
 /* FIXME: describe */
-extern void (*xalloc_fail_func) ();
+extern void (*xalloc_fail_func) (int);
 
 void *xmalloc PARAMS ((size_t n)) __attribute__ ((__malloc__));
 void *xmalloc_and_zero PARAMS ((size_t n)) __attribute__ ((__malloc__));

lib/xmalloc.c

@@ -56,7 +56,7 @@ int xalloc_exit_failure = EXIT_FAILURE;
 char *const xalloc_msg_memory_exhausted = "Memory exhausted";
 
 /* FIXME: describe */
-void (*xalloc_fail_func) (int) = 0;
+void (*xalloc_fail_func) (int) = NULL;
 
 static void
 xalloc_fail (int size)
@@ -70,13 +70,12 @@ xalloc_fail (int size)
 /* Allocate N bytes of memory dynamically, with error checking.  */
 
 void *
-xmalloc (n)
-     size_t n;
+xmalloc (size_t n)
 {
   void *p;
 
   p = malloc (n);
-  if (p == 0)
+  if (p == NULL)
     xalloc_fail ((int)n);
   return p;
 }
@@ -84,13 +83,12 @@ xmalloc (n)
 /* Allocate N bytes of memory dynamically, and set it all to zero. */
 
 void *
-xmalloc_and_zero (n)
-     size_t n;
+xmalloc_and_zero (size_t n)
 {
   void *p;
 
   p = malloc (n);
-  if (p == 0)
+  if (p == NULL)
     xalloc_fail ((int)n);
   memset (p, '\0', n);
   return p;
@@ -101,12 +99,10 @@ xmalloc_and_zero (n)
    If P is NULL, run xmalloc.  */
 
 void *
-xrealloc (p, n)
-     void *p;
-     size_t n;
+xrealloc (void *p, size_t n)
 {
   p = realloc (p, n);
-  if (p == 0)
+  if (p == NULL)
     xalloc_fail (n);
   return p;
 }
@@ -134,7 +130,7 @@ xcalloc (n, s)
   void *p;
 
   p = calloc (n, s);
-  if (p == 0)
+  if (p == NULL)
     xalloc_fail ();
   return p;
 }