implement wordexp. first try, may be buggy. intended to be safe.

src/misc/wordexp.c

+#include <wordexp.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+static char *getword(FILE *f)
+{
+	char *s = 0;
+	return getdelim(&s, (size_t [1]){0}, 0, f) < 0 ? 0 : s;
+}
+
+int wordexp(const char *s, wordexp_t *we, int flags)
+{
+	size_t i, l, len;
+	int sq=0, dq=0;
+	size_t np=0;
+	char *cmd, *w, **tmp;
+	char *redir = (flags & WRDE_SHOWERR) ? "" : "2>/dev/null";
+	int err = 0, status;
+	FILE *f;
+	size_t wc = 0;
+	char **wv = 0;
+
+	if (flags & WRDE_REUSE) wordfree(we);
+
+	if (flags & WRDE_NOCMD) for (i=0; s[i]; i++) switch (s[i]) {
+	case '\\':
+		if (!sq) i++;
+		break;
+	case '\'':
+		if (!dq) sq^=1;
+		break;
+	case '"':
+		if (!sq) dq^=1;
+		break;
+	case '(':
+		if (np) {
+			np++;
+			break;
+		}
+	case ')':
+		if (np) {
+			np--;
+			break;
+		}
+	case '\n':
+	case '|':
+	case '&':
+	case ';':
+	case '<':
+	case '>':
+	case '{':
+	case '}':
+		if (!(sq|dq|np)) return WRDE_BADCHAR;
+		break;
+	case '$':
+		if (s[i+1]=='(' && s[i+2]=='(') {
+			i += 2;
+			np += 2;
+			break;
+		} else if (s[i+1] != '(') break;
+	case '`':
+		if (sq) break;
+		return WRDE_CMDSUB;
+	}
+
+	if (flags & WRDE_APPEND) {
+		wc = we->we_wordc;
+		wv = we->we_wordv;
+	}
+
+	i = wc;
+	if (flags & WRDE_DOOFFS) {
+		if (we->we_offs > SIZE_MAX/sizeof(void *)/4)
+			return WRDE_NOSPACE;
+		i += we->we_offs;
+	}
+
+	len = 50 + strlen(s);
+	cmd = malloc(len);
+	if (!cmd) return WRDE_NOSPACE;
+	snprintf(cmd, len, "printf %%s\\\\0 %s %s", s, redir);
+printf("{%s}\n", cmd);
+	f = popen(cmd, "r");
+	free(cmd);
+	if (!f) return WRDE_NOSPACE;
+
+	l = wv ? i+1 : 0;
+
+	while ((w = getword(f))) {
+		if (i+1 >= l) {
+			l += l/2+10;
+			tmp = realloc(wv, l*sizeof(char *));
+			if (!tmp) break;
+			wv = tmp;
+		}
+		wv[i++] = w;
+		wv[i] = 0;
+	}
+	if (!feof(f)) err = WRDE_NOSPACE;
+
+	status = pclose(f);
+	if (WEXITSTATUS(status)) {
+		if (!(flags & WRDE_APPEND)) {
+			free(wv);
+			return WRDE_SYNTAX;
+		} else if (wv==we->we_wordv) {
+			return WRDE_SYNTAX;
+		}
+	}
+
+	we->we_wordv = wv;
+	we->we_wordc = i - we->we_offs;
+	return err;
+}
+
+void wordfree(wordexp_t *we)
+{
+	size_t i;
+	if (!we->we_wordv) return;
+	for (i=0; i<we->we_wordc; i++) free(we->we_wordv[we->we_offs+i]);
+	free(we->we_wordv);
+	we->we_wordv = 0;
+	we->we_wordc = 0;
+}