first pass at ppp-watch

1 files changed, 377 insertions, 0 deletions

diff --git a/src/shvar.c b/src/shvar.c
new file mode 100644
index 00000000..5c5233e1
--- /dev/null
+++ b/src/shvar.c
@@ -0,0 +1,377 @@
+/* copied from rp3 -- DO NOT EDIT HERE, ONLY COPY FROM rp3 */
+/*
+ * shvar.c
+ *
+ * Implementation of non-destructively reading/writing files containing
+ * only shell variable declarations and full-line comments.
+ *
+ * Includes explicit inheritance mechanism intended for use with
+ * Red Hat Linux ifcfg-* files.  There is no protection against
+ * inheritance loops; they will generally cause stack overflows.
+ * Furthermore, they are only intended for one level of inheritance;
+ * the value setting algorithm assumes this.
+ *
+ * Copyright 1999 Red Hat, Inc.
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <assert.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "shvar.h"
+
+/* Open the file <name>, return shvarFile on success, NULL on failure */
+shvarFile *
+svNewFile(char *name)
+{
+    shvarFile *s = NULL;
+    int closefd = 0;
+
+    s = calloc(sizeof(shvarFile), 1);
+    if (!s) return NULL;
+
+    s->fd = open(name, O_RDWR); /* NOT O_CREAT */
+    if (s->fd == -1) {
+	/* try read-only */
+	s->fd = open(name, O_RDONLY); /* NOT O_CREAT */
+	if (s->fd) closefd = 1;
+    }
+    s->fileName = strdup(name);
+
+    if (s->fd != -1) {
+	struct stat buf;
+	char *tmp;
+
+	if (fstat(s->fd, &buf) < 0) goto bail;
+	s->arena = calloc(buf.st_size, 1);
+	if (!s->arena) goto bail;
+	if (read(s->fd, s->arena, buf.st_size) < 0) goto bail;
+	/* Yes, I know that strtok is evil, except that this is
+	 * precisely what it was intended for in the first place...
+	 */
+	tmp = strtok(s->arena, "\n");
+	while (tmp) {
+	    s->lineList = g_list_append(s->lineList, tmp);
+	    tmp = strtok(NULL, "\n");
+	}
+	if (closefd) {
+	    close(s->fd);
+	    s->fd = -1;
+	}
+    }
+
+    return s;
+
+bail:
+    if (s->fd != -1) close(s->fd);
+    if (s->arena) free (s->arena);
+    if (s->fileName) free (s->fileName);
+    free (s);
+    return NULL;
+}
+
+/* remove escaped characters in place */
+static void
+unescape(char *s) {
+    int len, i;
+
+    len = strlen(s);
+    if ((s[0] == '"' || s[0] == '\'') && s[0] == s[len-1]) {
+	i = len - 2;
+	memmove(s, s+1, i);
+	s[i+1] = '\0';
+	len = i;
+    }
+    for (i = 0; i < len; i++) {
+	if (s[i] == '\\') {
+	    memmove(s+i, s+i+1, len-(i+1));
+	    len--;
+	}
+	s[len] = '\0';
+    }
+}
+
+
+/* create a new string with all necessary characters escaped.
+ * caller must free returned string
+ */
+static const char escapees[] = "\"'\\$~`";	/* must be escaped */
+static const char spaces[] = " \t";		/* only require "" */
+static char *
+escape(char *s) {
+    char *new;
+    int i, j, mangle = 0, space = 0;
+    int newlen, slen;
+    static int esclen, splen;
+
+    if (!esclen) esclen = strlen(escapees);
+    if (!splen) splen = strlen(spaces);
+    for (i = 0; i < esclen; i++) {
+	if (strchr(s, escapees[i])) mangle++;
+    }
+    for (i = 0; i < splen; i++) {
+	if (strchr(s, spaces[i])) space++;
+    }
+    if (!mangle && !space) return strdup(s);
+
+    slen = strlen(s);
+    newlen = slen + mangle + 3;	/* 3 is extra ""\0 */
+    new = calloc(newlen, 1);
+    if (!new) return NULL;
+
+    new[0] = '"';
+    for (i = 0, j = 1; i < slen; i++, j++) {
+	if (strchr(escapees, s[i])) {
+	    new[j++] = '\\';
+	}
+	new[j] = s[i];
+    }
+    new[j] = '"';
+
+    return new;
+}
+
+/* Get the value associated with the key, and leave the current pointer
+ * pointing at the line containing the value.  The char* returned MUST
+ * be freed by the caller.
+ */
+char *
+svGetValue(shvarFile *s, char *key)
+{
+    char *value = NULL;
+    char *line;
+    char *keyString;
+    int len;
+
+    assert(s);
+    assert(key);
+
+    keyString = calloc (strlen(key) + 2, 1);
+    if (!keyString) return NULL;
+    strcpy(keyString, key);
+    keyString[strlen(key)] = '=';
+    len = strlen(keyString);
+
+    for (s->current = s->lineList; s->current; s->current = s->current->next) {
+	line = s->current->data;
+	if (!strncmp(keyString, line, len)) {
+	    value = strdup(line + len);
+	    unescape(value);
+	    break;
+	}
+    }
+    free(keyString);
+
+    if (value) {
+	if (value[0]) {
+	    return value;
+	} else {
+	    free (value);
+	    return NULL;
+	}
+    }
+    if (s->parent) value = svGetValue(s->parent, key);
+    return value;
+}
+
+/* return 1 if <key> resolves to any truth value (e.g. "yes", "y", "true")
+ * return 0 if <key> resolves to any non-truth value (e.g. "no", "n", "false")
+ * return <default> otherwise
+ */
+int
+svTrueValue(shvarFile *s, char *key, int def)
+{
+    char *tmp;
+    int returnValue = def;
+
+    tmp = svGetValue(s, key);
+    if (!tmp) return returnValue;
+
+    if ( (!strcasecmp("yes", tmp)) ||
+	 (!strcasecmp("true", tmp)) ||
+	 (!strcasecmp("t", tmp)) ||
+	 (!strcasecmp("y", tmp)) ) returnValue = 1;
+    else
+    if ( (!strcasecmp("no", tmp)) ||
+	 (!strcasecmp("false", tmp)) ||
+	 (!strcasecmp("f", tmp)) ||
+	 (!strcasecmp("n", tmp)) ) returnValue = 0;
+
+    free (tmp);
+    return returnValue;
+}
+
+
+/* Set the variable <key> equal to the value <value>.
+ * If <key> does not exist, and the <current> pointer is set, append
+ * the key=value pair after that line.  Otherwise, prepend the pair
+ * to the top of the file.  Here's the algorithm, as the C code
+ * seems to be rather dense:
+ *
+ * if (value == NULL), then:
+ *     if val2 (parent): change line to key= or append line key=
+ *     if val1 (this)  : delete line
+ *     else noop
+ * else use this table:
+ *                                val2
+ *             NULL              value               other
+ * v   NULL    append line       noop                append line
+ * a
+ * l   value   noop              noop                noop
+ * 1
+ *     other   change line       delete line         change line
+ *
+ * No changes are ever made to the parent config file, only to the
+ * specific file passed on the command line.
+ *
+ */
+void
+svSetValue(shvarFile *s, char *key, char *value)
+{
+    char *val1 = NULL, *val2 = NULL;
+    char *keyValue;
+
+    assert(s);
+    assert(key);
+    /* value may be NULL */
+
+    if (value) value = escape(value);
+    keyValue = malloc (strlen(key) + (value?strlen(value):0) + 2);
+    if (!keyValue) return;
+    sprintf(keyValue, "%s=%s", key, value?value:"");
+
+    val1 = svGetValue(s, key);
+    if (val1 && value && !strcmp(val1, value)) goto bail;
+    if (s->parent) val2 = svGetValue(s->parent, key);
+
+    if (!value) {
+	/* delete value somehow */
+	if (val2) {
+	    /* change/append line to get key= */
+	    if (s->current) s->current->data = keyValue;
+	    else s->lineList = g_list_append(s->lineList, keyValue);
+	    s->freeList = g_list_append(s->freeList, keyValue);
+	    s->modified = 1;
+	} else if (val1) {
+	    /* delete line */
+	    s->lineList = g_list_remove_link(s->lineList, s->current);
+	    g_list_free_1(s->current);
+	    s->modified = 1;
+	    goto bail; /* do not need keyValue */
+	}
+	goto end;
+    }
+
+    if (!val1) {
+	if (val2 && !strcmp(val2, value)) goto end;
+	/* append line */
+	s->lineList = g_list_append(s->lineList, keyValue);
+	s->freeList = g_list_append(s->freeList, keyValue);
+	s->modified = 1;
+	goto end;
+    }
+
+    /* deal with a whole line of noops */
+    if (val1 && !strcmp(val1, value)) goto end;
+
+    /* At this point, val1 && val1 != value */
+    if (val2 && !strcmp(val2, value)) {
+	/* delete line */
+	s->lineList = g_list_remove_link(s->lineList, s->current);
+	g_list_free_1(s->current);
+	s->modified = 1;
+	goto bail; /* do not need keyValue */
+    } else {
+	/* change line */
+	if (s->current) s->current->data = keyValue;
+	else s->lineList = g_list_append(s->lineList, keyValue);
+	s->freeList = g_list_append(s->freeList, keyValue);
+	s->modified = 1;
+    }
+
+end:
+    if (value) free(value);
+    if (val1) free(val1);
+    if (val2) free(val2);
+    return;
+
+bail:
+    if (keyValue) free (keyValue);
+    goto end;
+}
+
+/* Write the current contents iff modified.  Returns -1 on error
+ * and 0 on success.  Do not write if no values have been modified.
+ * The mode argument is only used if creating the file, not if
+ * re-writing an existing file, and is passed unchanged to the
+ * open() syscall.
+ */
+int
+svWriteFile(shvarFile *s, int mode)
+{
+    FILE *f;
+    int tmpfd;
+
+    if (s->modified) {
+	if (s->fd == -1)
+	    s->fd = open(s->fileName, O_WRONLY|O_CREAT, mode);
+	if (s->fd == -1)
+	    return -1;
+	if (ftruncate(s->fd, 0) < 0)
+	    return -1;
+
+	tmpfd = dup(s->fd);
+	f = fdopen(tmpfd, "w");
+	fseek(f, 0, SEEK_SET);
+	for (s->current = s->lineList; s->current; s->current = s->current->next) {
+	    char *line = s->current->data;
+	    fprintf(f, "%s\n", line);
+	}
+	fclose(f);
+    }
+
+    return 0;
+}
+
+ 
+/* Close the file descriptor (if open) and delete the shvarFile.
+ * Returns -1 on error and 0 on success.
+ */
+int
+svCloseFile(shvarFile *s)
+{
+
+    assert(s);
+
+    if (s->fd != -1) close(s->fd);
+
+    free(s->arena);
+    for (s->current = s->freeList; s->current; s->current = s->current->next) {
+        free(s->current->data);
+    }
+    free(s->fileName);
+    g_list_free(s->freeList);
+    g_list_free(s->lineList); /* implicitly frees s->current */
+    free(s);
+    return 0;
+}