rcx

commit c7333b81160c0ae825586046cd02db441ae107e5
parent 34049bf63711ae6c17f03e2721055864a19ee917
Author: robert <robertrussell.72001@gmail.com>
Date:   Sat, 30 Jul 2022 16:15:20 -0700

alloc: make overflows nonfatal

Diffstat:
M
src/alloc.c
 | 
39
+++++++++++++++++++++++++--------------

1 file changed, 25 insertions(+), 14 deletions(-)
diff --git a/src/alloc.c b/src/alloc.c
@@ -1,3 +1,4 @@
+#include <errno.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -9,21 +10,15 @@
  * (but not conversely). This lets us avoid division in overflow checks. */
 #define MUL_NO_OVERFLOW ((usize) 1 << (sizeof(usize) * 4))
 
-static bool
+static inline bool
 mul_will_overflow(usize a, usize b) {
 	return (a >= MUL_NO_OVERFLOW || b >= MUL_NO_OVERFLOW)
 		&& a > 0 && USIZE_MAX/a < b;
 }
 
-#define FAIL_OVERFLOW() fatalf("allocation failure: overflow")
-
-/* Compute a + b*c with overflow checks. */
-static usize
-addmul(usize a, usize b, usize c) {
-	if (mul_will_overflow(b, c)) FAIL_OVERFLOW();
-	usize bc = b * c;
-	if (a > USIZE_MAX - bc) FAIL_OVERFLOW();
-	return a + bc;
+static inline bool
+addmul_will_overflow(usize a, usize b, usize c) { /* a + b*c */
+	return mul_will_overflow(b, c) || a > USIZE_MAX - b*c;
 }
 
 void *
@@ -48,12 +43,20 @@ allocnz(usize len, usize size) {
 
 void *
 allocf(usize hsize, usize flen, usize fsize) {
-	return alloc(addmul(hsize, flen, fsize));
+	if (addmul_will_overflow(hsize, flen, fsize)) {
+		errno = ENOMEM;
+		return 0;
+	}
+	return alloc(hsize + flen*fsize);
 }
 
 void *
 allocfz(usize hsize, usize flen, usize fsize) {
-	return allocz(addmul(hsize, flen, fsize));
+	if (addmul_will_overflow(hsize, flen, fsize)) {
+		errno = ENOMEM;
+		return 0;
+	}
+	return allocz(hsize + flen*fsize);
 }
 
 void *
@@ -76,12 +79,20 @@ reallocnz(void *p, usize olen, usize nlen, usize size) {
 
 void *
 reallocf(void *p, usize hsize, usize flen, usize fsize) {
-	return realloc(p, addmul(hsize, flen, fsize));
+	if (addmul_will_overflow(hsize, flen, fsize)) {
+		errno = ENOMEM;
+		return 0;
+	}
+	return realloc(p, hsize + flen*fsize);
 }
 
 void *
 reallocfz(void *p, usize hsize, usize oflen, usize nflen, usize fsize) {
-	return reallocz(p, hsize + oflen*fsize, addmul(hsize, nflen, fsize));
+	if (addmul_will_overflow(hsize, nflen, fsize)) {
+		errno = ENOMEM;
+		return 0;
+	}
+	return reallocz(p, hsize + oflen*fsize, hsize + nflen*fsize);
 }
 
 #define EALLOC(name, ...)\