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SUSE:SLE-15-SP1:GA
emacs.21200
boo1180353-6d8144a2.patch
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File boo1180353-6d8144a2.patch of Package emacs.21200
From 6d8144a2abb1c37982d82e32c68ab5115aca792c Mon Sep 17 00:00:00 2001 From: Eli Zaretskii <eliz@gnu.org> Date: Wed, 31 Aug 2016 18:53:43 +0300 Subject: [PATCH] Avoid recursive calls in etags * lib-src/etags.c (stack_entry): New struct. (push_node, pop_node, put_entry): New functions. (free_tree, add_node, invalidate_nodes, put_entries): Re-implement in a non-recursive way, to avoid stack overflow. (Bug#5847) --- lib-src/etags.c | 290 +++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 226 insertions(+), 64 deletions(-) --- lib-src/etags.c +++ lib-src/etags.c 2021-09-09 10:05:43.577612833 +0000 @@ -2007,19 +2007,80 @@ pfnote (char *name, bool is_func, char * } /* + * Utility functions and data to avoid recursion. + */ + +typedef struct stack_entry { + node *np; + struct stack_entry *next; +} stkentry; + +static void +push_node (node *np, stkentry **stack_top) +{ + if (np) + { + stkentry *new = xnew (1, stkentry); + + new->np = np; + new->next = *stack_top; + *stack_top = new; + } +} + +static node * +pop_node (stkentry **stack_top) +{ + node *ret = NULL; + + if (*stack_top) + { + stkentry *old_start = *stack_top; + + ret = (*stack_top)->np; + *stack_top = (*stack_top)->next; + free (old_start); + } + return ret; +} + +/* * free_tree () - * recurse on left children, iterate on right children. + * emulate recursion on left children, iterate on right children. */ static void free_tree (register node *np) { + stkentry *stack = NULL; + while (np) { - register node *node_right = np->right; - free_tree (np->left); + register node *node_right; + + /* Descent on left children. */ + while (np->left) + { + push_node (np, &stack); + np = np->left; + } + /* Free node without left children. */ + node_right = np->right; free (np->name); free (np->regex); free (np); + if (!node_right) + { + /* Backtrack to find a node with right children, while freeing nodes + that don't have right children. */ + while (node_right == NULL && (np = pop_node (&stack)) != NULL) + { + node_right = np->right; + free (np->name); + free (np->regex); + free (np); + } + } + /* Free right children. */ np = node_right; } } @@ -2051,9 +2112,9 @@ free_fdesc (register fdesc *fdp) static void add_node (node *np, node **cur_node_p) { - register int dif; - register node *cur_node = *cur_node_p; + node *cur_node = *cur_node_p; + /* Make the first node. */ if (cur_node == NULL) { *cur_node_p = np; @@ -2075,51 +2136,77 @@ add_node (node *np, node **cur_node_p) last_node->right = np; last_node = np; } - else if (cur_node->fdp == np->fdp) + else { - /* Scanning the list we found the head of a sublist which is - good for us. Let's scan this sublist. */ - add_node (np, &cur_node->right); + while (cur_node->fdp != np->fdp) + { + if (cur_node->left == NULL) + break; + /* The head of this sublist is not good for us. Let's try the + next one. */ + cur_node = cur_node->left; + } + if (cur_node->left) + { + /* Scanning the list we found the head of a sublist which is + good for us. Let's scan this sublist. */ + if (cur_node->right) + { + cur_node = cur_node->right; + while (cur_node->right) + cur_node = cur_node->right; + } + /* Make a new node in this sublist. */ + cur_node->right = np; + } + else + { + /* Make a new sublist. */ + cur_node->left = np; + } + last_node = np; } - else - /* The head of this sublist is not good for us. Let's try the - next one. */ - add_node (np, &cur_node->left); } /* if ETAGS mode */ - else { /* Ctags Mode */ - dif = strcmp (np->name, cur_node->name); + register int dif; + node **next_node = &cur_node; - /* - * If this tag name matches an existing one, then - * do not add the node, but maybe print a warning. - */ - if (no_duplicates && !dif) + while ((cur_node = *next_node) != NULL) { - if (np->fdp == cur_node->fdp) + dif = strcmp (np->name, cur_node->name); + /* + * If this tag name matches an existing one, then + * do not add the node, but maybe print a warning. + */ + if (!dif && no_duplicates) { - if (!no_warnings) + if (np->fdp == cur_node->fdp) + { + if (!no_warnings) + { + fprintf (stderr, + "Duplicate entry in file %s, line %d: %s\n", + np->fdp->infname, lineno, np->name); + fprintf (stderr, "Second entry ignored\n"); + } + } + else if (!cur_node->been_warned && !no_warnings) { - fprintf (stderr, "Duplicate entry in file %s, line %d: %s\n", - np->fdp->infname, lineno, np->name); - fprintf (stderr, "Second entry ignored\n"); + fprintf + (stderr, + "Duplicate entry in files %s and %s: %s (Warning only)\n", + np->fdp->infname, cur_node->fdp->infname, np->name); + cur_node->been_warned = true; } + return; } - else if (!cur_node->been_warned && !no_warnings) - { - fprintf - (stderr, - "Duplicate entry in files %s and %s: %s (Warning only)\n", - np->fdp->infname, cur_node->fdp->infname, np->name); - cur_node->been_warned = true; - } - return; + else + next_node = dif < 0 ? &cur_node->left : &cur_node->right; } - - /* Actually add the node */ - add_node (np, dif < 0 ? &cur_node->left : &cur_node->right); + *next_node = np; + last_node = np; } /* if CTAGS mode */ } @@ -2132,31 +2219,65 @@ static void invalidate_nodes (fdesc *badfdp, node **npp) { node *np = *npp; + stkentry *stack = NULL; if (np == NULL) return; if (CTAGS) { - if (np->left != NULL) - invalidate_nodes (badfdp, &np->left); - if (np->fdp == badfdp) - np->valid = false; - if (np->right != NULL) - invalidate_nodes (badfdp, &np->right); + while (np) + { + /* Push all the left children on the stack. */ + while (np->left != NULL) + { + push_node (np->left, &stack); + np = np->left; + } + /* Invalidate this node. */ + if (np->fdp == badfdp) + np->valid = false; + if (!np->right) + { + /* Pop nodes from stack, invalidating them, until we find one + with a right child. */ + do { + np = pop_node (&stack); + if (np->fdp == badfdp) + np->valid = false; + } while (np && np->right == NULL); + } + /* Process the right child, if any. */ + if (np) + np = np->right; + } } else { - assert (np->fdp != NULL); - if (np->fdp == badfdp) + node super_root, *np_parent; + + super_root.left = np; + super_root.fdp = (fdesc *)-1; + np = &super_root; + + while (np) { - *npp = np->left; /* detach the sublist from the list */ - np->left = NULL; /* isolate it */ - free_tree (np); /* free it */ - invalidate_nodes (badfdp, npp); + /* Descent on left children until node with BADFP. */ + while (np && np->fdp != badfdp) + { + assert (np->fdp != NULL); + np_parent = np; + np = np->left; + } + if (np) + { + np_parent->left = np->left; /* detach subtree from the tree */ + np->left = NULL; /* isolate it */ + free_tree (np); /* free it */ + np = np_parent->left; /* continue with rest of tree */ + } } - else - invalidate_nodes (badfdp, &np->left); + *npp = super_root.left; } } @@ -2201,20 +2322,13 @@ total_size_of_entries (register node *np } static void -put_entries (register node *np) +put_entry (register node *np) { register char *sp; static fdesc *fdp = NULL; - if (np == NULL) - return; - - /* Output subentries that precede this one */ - if (CTAGS) - put_entries (np->left); - /* Output this entry */ - if (np->valid) + if (np && np->valid) { if (!CTAGS) { @@ -2278,11 +2392,59 @@ put_entries (register node *np) } } } /* if this node contains a valid tag */ +} - /* Output subentries that follow this one */ - put_entries (np->right); - if (!CTAGS) - put_entries (np->left); +static void +put_entries (register node *np) +{ + stkentry *stack = NULL; + + if (np == NULL) + return; + + if (CTAGS) + { + while (np) + { + /* Stack subentries that precede this one. */ + while (np->left) + { + push_node (np, &stack); + np = np->left; + } + /* Output this subentry. */ + put_entry (np); + /* Stack subentries that follow this one. */ + if (!np->right) + { + /* Output subentries that precede the next one. */ + do { + np = pop_node (&stack); + put_entry (np); + } while (np && np->right == NULL); + } + if (np) + np = np->right; + } + } + else + { + push_node (np, &stack); + while ((np = pop_node (&stack)) != NULL) + { + /* Output this subentry. */ + put_entry (np); + while (np->right) + { + /* Output subentries that follow this one. */ + put_entry (np->right); + /* Stack subentries from the following files. */ + push_node (np->left, &stack); + np = np->right; + } + push_node (np->left, &stack); + } + } }
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