view lib/llist.c @ 1613:96aa7ec74936 draft

Fix yet another sed bug. The s/// command would copy the \ of substitutions before deciding what to do with them (generally overwriting the \ with the new data). When the substitution was A) at the very end of the new string, B) resolved to nothing, it could leave a trailing \ that didn't belong there and didn't get overwritten because the "copy trailing data" part that copies the original string's null terminator already happened before the \ overwrote it. The ghostwheel() function restarts regexes after embedded NUL bytes, but if the string it's passed is _longer_ than the length it's told then it gets confused (and it means we're off the end of our allocation so segfaults are likely). Fix: test for \ first and move the "copy byte" logic into an else case.
author Rob Landley <>
date Mon, 15 Dec 2014 03:34:55 -0600
parents 4d898affda0c
line wrap: on
line source

/* llist.c - Linked list functions
 * Linked list structures have a next pointer as their first element.

#include "toys.h"

// Callback function to free data pointer of double_list or arg_list

void llist_free_arg(void *node)
  struct arg_list *d = node;


void llist_free_double(void *node)
  struct double_list *d = node;


// Call a function (such as free()) on each element of a linked list.
void llist_traverse(void *list, void (*using)(void *node))
  void *old = list;

  while (list) {
    void *pop = llist_pop(&list);

    // End doubly linked list too.
    if (old == list) break;

// Return the first item from the list, advancing the list (which must be called
// as &list)
void *llist_pop(void *list)
  // I'd use a void ** for the argument, and even accept the typecast in all
  // callers as documentation you need the &, except the stupid compiler
  // would then scream about type-punned pointers.  Screw it.
  void **llist = (void **)list;
  void **next = (void **)*llist;
  *llist = *next;

  return (void *)next;

void *dlist_pop(void *list)
  struct double_list **pdlist = (struct double_list **)list, *dlist = *pdlist;

  if (dlist->next == dlist) *pdlist = 0;
  else {
    dlist->next->prev = dlist->prev;
    dlist->prev->next = *pdlist = dlist->next;

  return dlist;

void dlist_add_nomalloc(struct double_list **list, struct double_list *new)
  if (*list) {
    new->next = *list;
    new->prev = (*list)->prev;
    (*list)->prev->next = new;
    (*list)->prev = new;
  } else *list = new->next = new->prev = new;

// Add an entry to the end of a doubly linked list
struct double_list *dlist_add(struct double_list **list, char *data)
  struct double_list *new = xmalloc(sizeof(struct double_list));

  new->data = data;
  dlist_add_nomalloc(list, new);

  return new;

// Terminate circular list for traversal in either direction. Returns end *.
void *dlist_terminate(void *list)
  struct double_list *end = list;

  if (!list) return 0;

  end = end->prev;
  end->next->prev = 0;
  end->next = 0;

  return end;