Add pv_asprintf() and change the way the terminal lock file is stored, so it is in a dynamically allocated buffer rather than using one of a fixed size.

src/include/pv-internal.h

@@ -139,7 +139,7 @@ struct pvwatchfd_s;
 typedef /*@null@*/ struct pvwatchfd_s *pvwatchfd_t;
 
 /* String pointer, that is the only pointer to this resource, that can be null. */
-typedef /*@only@*/ /*@null@*/ char * nullable_string_t;
+typedef /*@only@*/ /*@null@*/ char * nullable_only_string_t;
 
 /*
  * Structure for holding PV internal state. Opaque outside the PV library.
@@ -163,7 +163,7 @@ struct pvstate_s {
 	 * Input files *
 	 ***************/
 	struct pvinputfiles_s {
-		/*@only@*/ /*@null@*/ nullable_string_t *filename; /* input filenames */
+		/*@only@*/ /*@null@*/ nullable_only_string_t *filename; /* input filenames */
 		unsigned int file_count;	 /* number of input files */
 	} files;
 
@@ -370,7 +370,7 @@ struct pvstate_s {
 	 * Cursor/IPC state *
 	 ********************/
 	struct pvcursorstate_s {
-		char lock_file[PV_SIZEOF_CRS_LOCK_FILE];
+		/*@only@*/ /*@null@*/ char *lock_file;	/* terminal lock filename */
 #ifdef HAVE_IPC
 		/*@keep@*/ /*@null@*/ struct pvipccursorstate_s *shared; /* data shared between instances */
 		int shmid;		 /* ID of our shared memory segment */

src/include/pv.h

@@ -98,12 +98,27 @@ extern double pv_percentage(off_t, const off_t);
  * String handling wrappers.
  */
 
+/* String pointer that can be null. */
+typedef /*@null@*/ char * nullable_string_ptr;
+
 /*
  * Wrapper for sprintf(), falling back to sprintf() on systems without that
  * function.
  */
 extern int pv_snprintf(char *, size_t, const char *, ...);
 
+/*
+ * Wrapper for snprintf(), falling back to sprintf() on systems without that
+ * function.
+ */
+extern int pv_snprintf(char *, size_t, const char *, ...);
+
+/*
+ * Wrapper for asprintf(), providing an equivalent on systems without that
+ * function.
+ */
+extern int pv_asprintf(nullable_string_ptr *, const char *, ...);
+
 /*
  * Implementation of strlcat() where it is unavailable: append a string to a
  * buffer, constraining the buffer to a particular size and ensuring
@@ -115,7 +130,7 @@ extern size_t pv_strlcat(char *, const char *, size_t);
  * Allocate and return a duplicate of a \0-terminated string, ensuring that
  * the duplicate is also \0-terminated.  Returns NULL on error.
  */
-/*@null@ */ /*@only@ */ extern char *pv_strdup(const char *);
+/*@null@ */ /*@only@ */ extern char *pv_strdup(const /*@null@ */ char *);
 
 /*
  * Return a pointer to the last matching character in the buffer, or NULL if