make passwd/group functions safe against cancellation in stdio

these changes are a prerequisite to making stdio cancellable.

src/passwd/getgr_r.c

 #include "pwf.h"
+#include <pthread.h>
 
 #define FIX(x) (gr->gr_##x = gr->gr_##x-line+buf)
 
@@ -11,9 +12,15 @@ static int getgr_r(const char *name, gid_t gid, struct group *gr, char *buf, siz
 	size_t nmem = 0;
 	int rv = 0;
 	size_t i;
+	int cs;
+
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
 
 	f = fopen("/etc/group", "rb");
-	if (!f) return errno;
+	if (!f) {
+		rv = errno;
+		goto done;
+	}
 
 	*res = 0;
 	while (__getgrent_a(f, gr, &line, &len, &mem, &nmem)) {
@@ -39,6 +46,8 @@ static int getgr_r(const char *name, gid_t gid, struct group *gr, char *buf, siz
  	free(mem);
  	free(line);
 	fclose(f);
+done:
+	pthread_setcancelstate(cs, 0);
 	return rv;
 }
 

src/passwd/getgrent_a.c

 #include "pwf.h"
+#include <pthread.h>
 
 struct group *__getgrent_a(FILE *f, struct group *gr, char **line, size_t *size, char ***mem, size_t *nmem)
 {
 	ssize_t l;
 	char *s, *mems;
 	size_t i;
-
+	int cs;
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
 	for (;;) {
 		if ((l=getline(line, size, f)) < 0) {
 			free(*line);
 			*line = 0;
-			return 0;
+			gr = 0;
+			goto end;
 		}
 		line[0][l-1] = 0;
 
@@ -46,5 +49,7 @@ struct group *__getgrent_a(FILE *f, struct group *gr, char **line, size_t *size,
 		mem[0][0] = 0;
 	}
 	gr->gr_mem = *mem;
+end:
+	pthread_setcancelstate(cs, 0);
 	return gr;
 }

src/passwd/getpw_r.c

 #include "pwf.h"
+#include <pthread.h>
 
 #define FIX(x) (pw->pw_##x = pw->pw_##x-line+buf)
 
@@ -8,9 +9,15 @@ static int getpw_r(const char *name, uid_t uid, struct passwd *pw, char *buf, si
 	char *line = 0;
 	size_t len = 0;
 	int rv = 0;
+	int cs;
+
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
 
 	f = fopen("/etc/passwd", "rb");
-	if (!f) return errno;
+	if (!f) {
+		rv = errno;
+		goto done;
+	}
 
 	*res = 0;
 	while (__getpwent_a(f, pw, &line, &len)) {
@@ -32,6 +39,8 @@ static int getpw_r(const char *name, uid_t uid, struct passwd *pw, char *buf, si
 	}
  	free(line);
 	fclose(f);
+done:
+	pthread_setcancelstate(cs, 0);
 	return rv;
 }
 

src/passwd/getpwent_a.c

 #include "pwf.h"
+#include <pthread.h>
 
 struct passwd *__getpwent_a(FILE *f, struct passwd *pw, char **line, size_t *size)
 {
 	ssize_t l;
 	char *s;
+	int cs;
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
 	for (;;) {
 		if ((l=getline(line, size, f)) < 0) {
 			free(*line);
 			*line = 0;
-			return 0;
+			pw = 0;
+			break;
 		}
 		line[0][l-1] = 0;
 
@@ -32,6 +36,8 @@ struct passwd *__getpwent_a(FILE *f, struct passwd *pw, char **line, size_t *siz
 		if (!(s = strchr(s, ':'))) continue;
 
 		*s++ = 0; pw->pw_shell = s;
-		return pw;
+		break;
 	}
+	pthread_setcancelstate(cs, 0);
+	return pw;
 }