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* $Id: eval.c,v 1.7 2005/06/29 14:24:26 daichik Exp $
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* Copyright (c) 2003, Raphael Manfredi
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*----------------------------------------------------------------------
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* This file is part of gtk-gnutella.
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* gtk-gnutella is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* gtk-gnutella is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with gtk-gnutella; if not, write to the Free Software
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*----------------------------------------------------------------------
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* @author Raphael Manfredi
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RCSID("$Id: eval.c,v 1.7 2005/06/29 14:24:26 daichik Exp $");
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#include "misc.h" /* For g_strlcpy() */
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#include "override.h" /* Must be the last header included */
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#define MAX_STRING 1024 /**< Max length for substitution */
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static guint32 common_dbg = 0; /**< XXX -- need to init lib's props --RAM */
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static GHashTable *constants;
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static gchar *get_home(void);
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static gchar *get_variable(gchar *s, gchar **end);
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* Create a constant string, or reuse an existing one if possible.
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* @returns a string atom.
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constant_make(gchar *s)
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v = (gchar *) g_hash_table_lookup(constants, s);
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return v; /* Already exists */
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g_hash_table_insert(constants, v, v);
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* Initialize string evaluation.
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constants = g_hash_table_new(g_str_hash, g_str_equal);
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constants_free_kv(gpointer key,
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gpointer unused_val, gpointer unused_x)
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* Cleanup local structures at shutdown time.
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g_hash_table_foreach(constants, constants_free_kv, NULL);
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g_hash_table_destroy(constants);
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* Insert value `val' at beginning of string `start'.
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* The string `start' is held in a buffer capable of holding a string of
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* `maxlen' bytes, and the string is currently `len' bytes long, with `start'
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* being at the offset `off' within buffer.
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* @return the pointer right after the inserted value.
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insert_value(gchar *val, gchar *start, gint off,
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gint len, gint maxlen)
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gint vlen = strlen(val);
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g_assert(len <= maxlen);
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g_assert(off >= 0 && off <= len);
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if (len + vlen > maxlen) {
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g_warning("ignoring variable substitution text \"%s\"", val);
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memmove(start + vlen, start, len + 1 - off);
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memmove(start, val, vlen);
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* Needs brief description here.
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* Substitutes variables from string:
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* - The leading "~" is replaced by the home directory.
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* - Variables like "$PATH" or "${PATH}" are replaced by their value, as
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* fetched from the environment, or the empty string if not found.
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* If given a NULL input, we return NULL.
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* @return string atom, which is not meant to be freed until exit time.
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eval_subst(const gchar *str)
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gchar buf[MAX_STRING];
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gchar *end = buf + sizeof(buf);
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len = g_strlcpy(buf, str, sizeof(buf));
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if (len >= sizeof(buf)) {
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g_warning("eval_subst: string too large for substitution (%d bytes)",
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return constant_make((gchar *) str);
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printf("eval_subst: on entry: \"%s\"\n", buf);
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for (p = buf, c = *p++; c; c = *p++) {
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gchar *start = p - 1;
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if (c == '~' && start == buf) { /* Leading ~ only */
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memmove(start, start + 1, len - (start - buf));
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g_assert((ssize_t) len >= 0);
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} else if (c == '$') {
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val = get_variable(p, &after);
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memmove(start, after, len + 1 - (after - buf));
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len -= after - start; /* Also removing leading '$' */
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g_assert((ssize_t) len >= 0);
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gchar *next = insert_value(
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val, start, start - buf, len, sizeof(buf) - 1);
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g_assert(len < sizeof(buf));
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g_assert(p <= (buf + len));
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printf("eval_subst: on exit: \"%s\"\n", buf);
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g_assert(len == strlen(buf));
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return constant_make(buf);
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* Compute the user's home directory.
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* Uses the HOME environment variable first, then the entry from /etc/passwd.
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* @return string atom.
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return atom_str_get(v);
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pp = getpwuid(getuid());
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return atom_str_get(pp->pw_dir);
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g_warning("Could not determine home directory");
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return atom_str_get("/");
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* Extract variable name from string `s', then fetch value from environment.
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* @return variable's value, or "" if not found and set `end' to the address
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* of the character right after the variable name.
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static gchar *get_variable(gchar *s, gchar **end)
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guchar *p = (guchar *) s;
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gboolean end_brace = FALSE;
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* Grab variable's name.
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if (!isalnum(c) && c != '_')
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if (end_brace && *p == '}')
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*end = (gchar *) (p + 1);
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* Get value from environment.
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value = getenv(name);
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printf("variable \"%s\" is \"%s\"\n", name, value);
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/* vi: set ts=4 sw=4 cindent: */
added
removed
src/lib/eval.c
