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authorrsc <rsc>2007-08-24 20:20:23 +0000
committerrsc <rsc>2007-08-24 20:20:23 +0000
commite0e7d07e5afc1a073b659cbf0b8594071f05a816 (patch)
treeca49d4be6d276c241ef2fff485c34b72090ce0f0
parent5af5f6aa7f52db85f0f22555ae39395dbe68b731 (diff)
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test that fork fails gracefully
-rw-r--r--Makefile14
-rw-r--r--forktest.c54
-rw-r--r--usertests.c39
3 files changed, 103 insertions, 4 deletions
diff --git a/Makefile b/Makefile
index e12ddf1..31bc946 100644
--- a/Makefile
+++ b/Makefile
@@ -72,9 +72,9 @@ vectors.S : vectors.pl
ULIB = ulib.o usys.o printf.o umalloc.o
-usertests : usertests.o $(ULIB)
- $(LD) -N -e main -Ttext 0 -o usertests usertests.o $(ULIB)
- $(OBJDUMP) -S usertests > usertests.asm
+_usertests : usertests.o $(ULIB)
+ $(LD) -N -e main -Ttext 0 -o _usertests usertests.o $(ULIB)
+ $(OBJDUMP) -S _usertests > usertests.asm
_echo : echo.o $(ULIB)
$(LD) -N -e main -Ttext 0 -o _echo echo.o $(ULIB)
@@ -117,10 +117,16 @@ _zombie: zombie.o $(ULIB)
$(LD) -N -e main -Ttext 0 -o _zombie zombie.o $(ULIB)
$(OBJDUMP) -S _zombie > zombie.asm
+_forktest: forktest.o $(ULIB)
+ # forktest has less library code linked in - needs to be small
+ # in order to be able to max out the proc table.
+ $(LD) -N -e main -Ttext 0 -o _forktest forktest.o ulib.o usys.o
+ $(OBJDUMP) -S _forktest > forktest.asm
+
mkfs : mkfs.c fs.h
cc -o mkfs mkfs.c
-UPROGS=usertests _echo _cat _init _kill _ln _ls _mkdir _rm _sh _zombie
+UPROGS=_usertests _echo _cat _init _kill _ln _ls _mkdir _rm _sh _zombie _forktest
fs.img : mkfs README $(UPROGS)
./mkfs fs.img README $(UPROGS)
diff --git a/forktest.c b/forktest.c
new file mode 100644
index 0000000..90cc38c
--- /dev/null
+++ b/forktest.c
@@ -0,0 +1,54 @@
+// Test that fork fails gracefully.
+// Tiny executable so that the limit can be filling the proc table.
+
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+
+void
+printf(int fd, char *s, ...)
+{
+ write(fd, s, strlen(s));
+}
+
+void
+forktest(void)
+{
+ int n, pid;
+
+ printf(1, "fork test\n");
+
+ for(n=0; n<1000; n++){
+ pid = fork();
+ if(pid < 0)
+ break;
+ if(pid == 0)
+ exit();
+ }
+
+ if(n == 1000){
+ printf(1, "fork claimed to work 1000 times!\n");
+ exit();
+ }
+
+ for(; n > 0; n--){
+ if(wait() < 0){
+ printf(1, "wait stopped early\n");
+ exit();
+ }
+ }
+
+ if(wait() != -1){
+ printf(1, "wait got too many\n");
+ exit();
+ }
+
+ printf(1, "fork test OK\n");
+}
+
+int
+main(void)
+{
+ forktest();
+ exit();
+}
diff --git a/usertests.c b/usertests.c
index 3a9cd9a..17c7044 100644
--- a/usertests.c
+++ b/usertests.c
@@ -1189,6 +1189,44 @@ iref(void)
printf(1, "empty file name OK\n");
}
+// test that fork fails gracefully
+// the forktest binary also does this, but it runs out of proc entries first.
+// inside the bigger usertests binary, we run out of memory first.
+void
+forktest(void)
+{
+ int n, pid;
+
+ printf(1, "fork test\n");
+
+ for(n=0; n<1000; n++){
+ pid = fork();
+ if(pid < 0)
+ break;
+ if(pid == 0)
+ exit();
+ }
+
+ if(n == 1000){
+ printf(1, "fork claimed to work 1000 times!\n");
+ exit();
+ }
+
+ for(; n > 0; n--){
+ if(wait() < 0){
+ printf(1, "wait stopped early\n");
+ exit();
+ }
+ }
+
+ if(wait() != -1){
+ printf(1, "wait got too many\n");
+ exit();
+ }
+
+ printf(1, "fork test OK\n");
+}
+
int
main(int argc, char *argv[])
{
@@ -1223,6 +1261,7 @@ main(int argc, char *argv[])
sharedfd();
dirfile();
iref();
+ forktest();
exectest();