/*
	glob from musl (https://www.musl-libc.org/).

	MIT licensed:

----------------------------------------------------------------------
Copyright © 2005-2020 Rich Felker, et al.

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
----------------------------------------------------------------------
*/
#include "libbb.h"
#include <glob.h>
#include <fnmatch.h>

struct match
{
	struct match *next;
	char name[];
};

static int append(struct match **tail, const char *name, size_t len, int mark)
{
	struct match *new = malloc(sizeof(struct match) + len + 2);
	if (!new) return -1;
	(*tail)->next = new;
	new->next = NULL;
	memcpy(new->name, name, len+1);
	if (mark && len && name[len-1]!='/') {
		new->name[len] = '/';
		new->name[len+1] = 0;
	}
	*tail = new;
	return 0;
}

static int do_glob(char *buf, size_t pos, int type, char *pat, int flags, int (*errfunc)(const char *path, int err), struct match **tail)
{
	ptrdiff_t i, j;
	int in_bracket, overflow;
	char *p2, saved_sep;
	int readerr, old_errno;
	DIR *dir;
	struct dirent *de;

	/* If GLOB_MARK is unused, we don't care about type. */
	if (!type && !(flags & GLOB_MARK)) type = DT_REG;

	/* Special-case the remaining pattern being all slashes, in
	 * which case we can use caller-passed type if it's a dir. */
	if (*pat && type!=DT_DIR) type = 0;
	while (pos+1 < PATH_MAX && *pat=='/') buf[pos++] = *pat++;

	/* Consume maximal [escaped-]literal prefix of pattern, copying
	 * and un-escaping it to the running buffer as we go. */
	i=0; j=0;
	in_bracket = 0; overflow = 0;
	for (; pat[i]!='*' && pat[i]!='?' && (!in_bracket || pat[i]!=']'); i++) {
		if (!pat[i]) {
			if (overflow) return 0;
			pat += i;
			pos += j;
			i = j = 0;
			break;
		} else if (pat[i] == '[') {
			in_bracket = 1;
		} else if (pat[i] == '\\' && !(flags & GLOB_NOESCAPE)) {
			/* Backslashes inside a bracket are (at least by
			 * our interpretation) non-special, so if next
			 * char is ']' we have a complete expression. */
			if (in_bracket && pat[i+1]==']') break;
			/* Unpaired final backslash never matches. */
			if (!pat[i+1]) return 0;
			i++;
		}
		if (pat[i] == '/') {
			if (overflow) return 0;
			in_bracket = 0;
			pat += i+1;
			i = -1;
			pos += j+1;
			j = -1;
		}
		/* Only store a character if it fits in the buffer, but if
		 * a potential bracket expression is open, the overflow
		 * must be remembered and handled later only if the bracket
		 * is unterminated (and thereby a literal), so as not to
		 * disallow long bracket expressions with short matches. */
		if (pos+(j+1) < PATH_MAX) {
			buf[pos+j++] = pat[i];
		} else if (in_bracket) {
			overflow = 1;
		} else {
			return 0;
		}
		/* If we consume any new components, the caller-passed type
		 * or dummy type from above is no longer valid. */
		type = 0;
	}
	buf[pos] = 0;
	if (!*pat) {
		/* If we consumed any components above, or if GLOB_MARK is
		 * requested and we don't yet know if the match is a dir,
		 * we must confirm the file exists and/or determine its type.
		 *
		 * If marking dirs, symlink type is inconclusive; we need the
		 * type for the symlink target, and therefore must try stat
		 * first unless type is known not to be a symlink. Otherwise,
		 * or if that fails, use lstat for determining existence to
		 * avoid false negatives in the case of broken symlinks. */
		struct stat st;
		if ((flags & GLOB_MARK) && (!type||type==DT_LNK) && !stat(buf, &st)) {
			if (S_ISDIR(st.st_mode)) type = DT_DIR;
			else type = DT_REG;
		}
		if (!type && lstat(buf, &st)) {
			if (errno!=ENOENT && (errfunc(buf, errno) || (flags & GLOB_ERR)))
				return GLOB_ABORTED;
			return 0;
		}
		if (append(tail, buf, pos, (flags & GLOB_MARK) && type==DT_DIR))
			return GLOB_NOSPACE;
		return 0;
	}
	p2 = strchr(pat, '/');
	saved_sep = '/';
	/* Check if the '/' was escaped and, if so, remove the escape char
	 * so that it will not be unpaired when passed to fnmatch. */
	if (p2 && !(flags & GLOB_NOESCAPE)) {
		char *p;
		for (p=p2; p>pat && p[-1]=='\\'; p--);
		if ((p2-p)%2) {
			p2--;
			saved_sep = '\\';
		}
	}
	dir = opendir(pos ? buf : ".");
	if (!dir) {
		if (errfunc(buf, errno) || (flags & GLOB_ERR))
			return GLOB_ABORTED;
		return 0;
	}
	old_errno = errno;
	while (errno=0, de=readdir(dir)) {
		size_t l;
		int fnm_flags, r;

		/* Quickly skip non-directories when there's pattern left. */
		if (p2 && de->d_type && de->d_type!=DT_DIR && de->d_type!=DT_LNK)
			continue;

		l = strlen(de->d_name);
		if (l >= PATH_MAX-pos) continue;

		if (p2) *p2 = 0;

		fnm_flags= ((flags & GLOB_NOESCAPE) ? FNM_NOESCAPE : 0)
			| ((!(flags & GLOB_PERIOD)) ? FNM_PERIOD : 0);

		if (fnmatch(pat, de->d_name, fnm_flags))
			continue;

		/* With GLOB_PERIOD, don't allow matching . or .. unless
		 * fnmatch would match them with FNM_PERIOD rules in effect. */
		if (p2 && (flags & GLOB_PERIOD) && de->d_name[0]=='.'
		    && (!de->d_name[1] || (de->d_name[1]=='.' && !de->d_name[2]))
		    && fnmatch(pat, de->d_name, fnm_flags | FNM_PERIOD))
			continue;

		memcpy(buf+pos, de->d_name, l+1);
		if (p2) *p2 = saved_sep;
		r = do_glob(buf, pos+l, de->d_type, p2 ? p2 : (char *)"", flags, errfunc, tail);
		if (r) {
			closedir(dir);
			return r;
		}
	}
	readerr = errno;
	if (p2) *p2 = saved_sep;
	closedir(dir);
	if (readerr && (errfunc(buf, errno) || (flags & GLOB_ERR)))
		return GLOB_ABORTED;
	errno = old_errno;
	return 0;
}

static int ignore_err(const char *path UNUSED_PARAM, int err UNUSED_PARAM)
{
	return 0;
}

static void freelist(struct match *head)
{
	struct match *match, *next;
	for (match=head->next; match; match=next) {
		next = match->next;
		free(match);
	}
}

#if !ENABLE_PLATFORM_MINGW32
static int sort(const void *a, const void *b)
{
	return strcmp(*(const char **)a, *(const char **)b);
}

static int expand_tilde(char **pat, char *buf, size_t *pos)
{
	char *p = *pat + 1;
	size_t i = 0;

	char delim, *name_end = __strchrnul(p, '/');
	if ((delim = *name_end)) *name_end++ = 0;
	*pat = name_end;

	char *home = *p ? NULL : getenv("HOME");
	if (!home) {
		struct passwd pw, *res;
		switch (*p ? getpwnam_r(p, &pw, buf, PATH_MAX, &res)
			   : getpwuid_r(getuid(), &pw, buf, PATH_MAX, &res)) {
		case ENOMEM:
			return GLOB_NOSPACE;
		case 0:
			if (!res)
		default:
				return GLOB_NOMATCH;
		}
		home = pw.pw_dir;
	}
	while (i < PATH_MAX - 2 && *home)
		buf[i++] = *home++;
	if (*home)
		return GLOB_NOMATCH;
	if ((buf[i] = delim))
		buf[++i] = 0;
	*pos = i;
	return 0;
}
#endif

int glob(const char *restrict pat, int flags, int (*errfunc)(const char *path, int err), glob_t *restrict g)
{
	struct match head = { .next = NULL }, *tail = &head;
	size_t cnt, i;
	size_t offs = (flags & GLOB_DOOFFS) ? g->gl_offs : 0;
	int error = 0;
	char buf[PATH_MAX];

	if (!errfunc) errfunc = ignore_err;

	if (!(flags & GLOB_APPEND)) {
		g->gl_offs = offs;
		g->gl_pathc = 0;
		g->gl_pathv = NULL;
	}

	if (*pat) {
		char *p = strdup(pat);
		size_t pos = 0;
		char *s = p;
		if (!p) return GLOB_NOSPACE;
		buf[0] = 0;
#if !ENABLE_PLATFORM_MINGW32
		if ((flags & (GLOB_TILDE | GLOB_TILDE_CHECK)) && *p == '~')
			error = expand_tilde(&s, buf, &pos);
		if (!error)
#endif
			error = do_glob(buf, pos, 0, s, flags, errfunc, &tail);
		free(p);
	}

	if (error == GLOB_NOSPACE) {
		freelist(&head);
		return error;
	}

	for (cnt=0, tail=head.next; tail; tail=tail->next, cnt++);
	if (!cnt) {
		if (flags & GLOB_NOCHECK) {
			tail = &head;
			if (append(&tail, pat, strlen(pat), 0))
				return GLOB_NOSPACE;
			cnt++;
		} else
			return GLOB_NOMATCH;
	}

	if (flags & GLOB_APPEND) {
		char **pathv = realloc(g->gl_pathv, (offs + g->gl_pathc + cnt + 1) * sizeof(char *));
		if (!pathv) {
			freelist(&head);
			return GLOB_NOSPACE;
		}
		g->gl_pathv = pathv;
		offs += g->gl_pathc;
	} else {
		g->gl_pathv = malloc((offs + cnt + 1) * sizeof(char *));
		if (!g->gl_pathv) {
			freelist(&head);
			return GLOB_NOSPACE;
		}
		for (i=0; i<offs; i++)
			g->gl_pathv[i] = NULL;
	}
	for (i=0, tail=head.next; i<cnt; tail=tail->next, i++)
		g->gl_pathv[offs + i] = tail->name;
	g->gl_pathv[offs + i] = NULL;
	g->gl_pathc += cnt;

#if !ENABLE_PLATFORM_MINGW32
	if (!(flags & GLOB_NOSORT))
		qsort(g->gl_pathv+offs, cnt, sizeof(char *), sort);
#endif

	return error;
}

void globfree(glob_t *g)
{
	size_t i;
	for (i=0; i<g->gl_pathc; i++)
		free(g->gl_pathv[g->gl_offs + i] - offsetof(struct match, name));
	free(g->gl_pathv);
	g->gl_pathc = 0;
	g->gl_pathv = NULL;
}