Coding Guidelines/String Functions

Amanda provides a library of string functions with names that parse like this:

new|v|stralloc|f

as well as a few others (described below). The entire set of functions appears in amanda.h. The functions are all implemented as macros to debug functions, to allow tracing of file/line numbers.

The base function is, of course, stralloc, which simply allocates enough space, and then copies the string it is given as an argument. Adding new means that the first argument is a dynamically allocated string which this function will be replacing: if it is not NULL, it will be freed after the new string is allocated and constructed. This allows code like

{
  char *tmp = NULL;
  tmp = newstralloc(tmp, "first string");
  /* ... */
  tmp = newstralloc(tmp, "second string");
  /* ... */
  amfree(tmp);
}

without worrying about memory leaks (since each newstralloc invocation will free(tmp) if it is non-NULL).

Adding v to a function name indicates that it is variadic - that is, that it takes a variable number of arguments. Variadic functions which end in f act like printf, with the format as the first (or second, in the case of new* functions) argument. Variadic functions without f must be given a NULL as the final argument. Examples:

tmp = newvstrallocf(tmp, "could not open '%s': %s", filename, strerror(errno));
*errmsg = vstralloc(TMPDIR, "/foo/", filename, NULL);

Misc Functions

The function stralloc2 is a simple concatenation option; stralloc2(x, y) is equivalent to vstralloc(x, y, NULL).

The function strappend is a macro which appends its second argument to its first. strappend(x, y) is equivalent to newvstralloc(x, x, y, NULL).