Add pg_add_size_overflow() and friends

Commit 600086f47 added (several bespoke copies of) size_t addition with
overflow checks to libpq. Move this to common/int.h, along with
its subtraction and multiplication counterparts.

pg_neg_size_overflow() is intentionally omitted; I'm not sure we should
add SSIZE_MAX to win32_port.h for the sake of a function with no
callers.

Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/CAOYmi%2B%3D%2BpqUd2MUitvgW1pAJuXgG_TKCVc3_Ek7pe8z9nkf%2BAg%40mail.gmail.com

diff --git a/src/include/common/int.h b/src/include/common/int.h
index 3973f13379d86ad5b017de8204c9d0120baa36c6..435716b79062f4a99d4fbc22f864cdb05b3afbaf 100644 (file)
--- a/src/include/common/int.h
+++ b/src/include/common/int.h
@@ -601,6 +601,73 @@ pg_neg_u64_overflow(uint64 a, int64 *result)
 #endif
 }
 
+/*
+ * size_t
+ */
+static inline bool
+pg_add_size_overflow(size_t a, size_t b, size_t *result)
+{
+#if defined(HAVE__BUILTIN_OP_OVERFLOW)
+   return __builtin_add_overflow(a, b, result);
+#else
+   size_t      res = a + b;
+
+   if (res < a)
+   {
+       *result = 0x5EED;       /* to avoid spurious warnings */
+       return true;
+   }
+   *result = res;
+   return false;
+#endif
+}
+
+static inline bool
+pg_sub_size_overflow(size_t a, size_t b, size_t *result)
+{
+#if defined(HAVE__BUILTIN_OP_OVERFLOW)
+   return __builtin_sub_overflow(a, b, result);
+#else
+   if (b > a)
+   {
+       *result = 0x5EED;       /* to avoid spurious warnings */
+       return true;
+   }
+   *result = a - b;
+   return false;
+#endif
+}
+
+static inline bool
+pg_mul_size_overflow(size_t a, size_t b, size_t *result)
+{
+#if defined(HAVE__BUILTIN_OP_OVERFLOW)
+   return __builtin_mul_overflow(a, b, result);
+#else
+   size_t      res = a * b;
+
+   if (a != 0 && b != res / a)
+   {
+       *result = 0x5EED;       /* to avoid spurious warnings */
+       return true;
+   }
+   *result = res;
+   return false;
+#endif
+}
+
+/*
+ * pg_neg_size_overflow is currently omitted, to avoid having to reason about
+ * the portability of SSIZE_MIN/_MAX before a use case exists.
+ */
+/*
+ * static inline bool
+ * pg_neg_size_overflow(size_t a, ssize_t *result)
+ * {
+ *     ...
+ * }
+ */
+
 /*------------------------------------------------------------------------
  *
  * Comparison routines for integer types.

diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index dcc8a447d66f92847036546f2aba4e949f0b6318..7ab33930a3948fe16a669d5191ae238e6f8b8f50 100644 (file)
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -24,6 +24,7 @@
 #include <unistd.h>
 #endif
 
+#include "common/int.h"
 #include "libpq-fe.h"
 #include "libpq-int.h"
 #include "mb/pg_wchar.h"
@@ -4220,27 +4221,6 @@ PQescapeString(char *to, const char *from, size_t length)
 }
 
 
-/*
- * Frontend version of the backend's add_size(), intended to be API-compatible
- * with the pg_add_*_overflow() helpers. Stores the result into *dst on success.
- * Returns true instead if the addition overflows.
- *
- * TODO: move to common/int.h
- */
-static bool
-add_size_overflow(size_t s1, size_t s2, size_t *dst)
-{
-   size_t      result;
-
-   result = s1 + s2;
-   if (result < s1 || result < s2)
-       return true;
-
-   *dst = result;
-   return false;
-}
-
-
 /*
  * Escape arbitrary strings.  If as_ident is true, we escape the result
  * as an identifier; if false, as a literal.  The result is returned in
@@ -4324,14 +4304,14 @@ PQescapeInternal(PGconn *conn, const char *str, size_t len, bool as_ident)
     * Allocate output buffer. Protect against overflow, in case the caller
     * has allocated a large fraction of the available size_t.
     */
-   if (add_size_overflow(input_len, num_quotes, &result_size) ||
-       add_size_overflow(result_size, 3, &result_size))    /* two quotes plus a NUL */
+   if (pg_add_size_overflow(input_len, num_quotes, &result_size) ||
+       pg_add_size_overflow(result_size, 3, &result_size)) /* two quotes plus a NUL */
        goto overflow;
 
    if (!as_ident && num_backslashes > 0)
    {
-       if (add_size_overflow(result_size, num_backslashes, &result_size) ||
-           add_size_overflow(result_size, 2, &result_size))    /* for " E" prefix */
+       if (pg_add_size_overflow(result_size, num_backslashes, &result_size) ||
+           pg_add_size_overflow(result_size, 2, &result_size)) /* for " E" prefix */
            goto overflow;
    }
 
@@ -4493,9 +4473,9 @@ PQescapeByteaInternal(PGconn *conn,
    if (use_hex)
    {
        /* We prepend "\x" and double each input character. */
-       if (add_size_overflow(len, bslash_len + 1, &len) ||
-           add_size_overflow(len, from_length, &len) ||
-           add_size_overflow(len, from_length, &len))
+       if (pg_add_size_overflow(len, bslash_len + 1, &len) ||
+           pg_add_size_overflow(len, from_length, &len) ||
+           pg_add_size_overflow(len, from_length, &len))
            goto overflow;
    }
    else
@@ -4505,22 +4485,22 @@ PQescapeByteaInternal(PGconn *conn,
        {
            if (*vp < 0x20 || *vp > 0x7e)
            {
-               if (add_size_overflow(len, bslash_len + 3, &len))   /* octal "\ooo" */
+               if (pg_add_size_overflow(len, bslash_len + 3, &len))    /* octal "\ooo" */
                    goto overflow;
            }
            else if (*vp == '\'')
            {
-               if (add_size_overflow(len, 2, &len))    /* double each quote */
+               if (pg_add_size_overflow(len, 2, &len)) /* double each quote */
                    goto overflow;
            }
            else if (*vp == '\\')
            {
-               if (add_size_overflow(len, bslash_len * 2, &len))   /* double each backslash */
+               if (pg_add_size_overflow(len, bslash_len * 2, &len))    /* double each backslash */
                    goto overflow;
            }
            else
            {
-               if (add_size_overflow(len, 1, &len))
+               if (pg_add_size_overflow(len, 1, &len))
                    goto overflow;
            }
        }

diff --git a/src/interfaces/libpq/fe-print.c b/src/interfaces/libpq/fe-print.c
index cc667c9bac9713e294f6e7cb60572964867b16ac..fc153bee630c6995c0084e8502c1751e4aa8c960 100644 (file)
--- a/src/interfaces/libpq/fe-print.c
+++ b/src/interfaces/libpq/fe-print.c
@@ -33,6 +33,7 @@
 #endif
 #endif
 
+#include "common/int.h"
 #include "libpq-fe.h"
 #include "libpq-int.h"
 
@@ -451,27 +452,6 @@ do_field(const PQprintOpt *po, const PGresult *res,
 }
 
 
-/*
- * Frontend version of the backend's add_size(), intended to be API-compatible
- * with the pg_add_*_overflow() helpers. Stores the result into *dst on success.
- * Returns true instead if the addition overflows.
- *
- * TODO: move to common/int.h
- */
-static bool
-add_size_overflow(size_t s1, size_t s2, size_t *dst)
-{
-   size_t      result;
-
-   result = s1 + s2;
-   if (result < s1 || result < s2)
-       return true;
-
-   *dst = result;
-   return false;
-}
-
-
 static char *
 do_header(FILE *fout, const PQprintOpt *po, const int nFields, int *fieldMax,
          const char **fieldNames, unsigned char *fieldNotNum,
@@ -492,20 +472,20 @@ do_header(FILE *fout, const PQprintOpt *po, const int nFields, int *fieldMax,
        for (; n < nFields; n++)
        {
            /* Field plus separator, plus 2 extra '-' in standard format. */
-           if (add_size_overflow(tot, fieldMax[n], &tot) ||
-               add_size_overflow(tot, fs_len, &tot) ||
-               (po->standard && add_size_overflow(tot, 2, &tot)))
+           if (pg_add_size_overflow(tot, fieldMax[n], &tot) ||
+               pg_add_size_overflow(tot, fs_len, &tot) ||
+               (po->standard && pg_add_size_overflow(tot, 2, &tot)))
                goto overflow;
        }
        if (po->standard)
        {
            /* An extra separator at the front and back. */
-           if (add_size_overflow(tot, fs_len, &tot) ||
-               add_size_overflow(tot, fs_len, &tot) ||
-               add_size_overflow(tot, 2, &tot))
+           if (pg_add_size_overflow(tot, fs_len, &tot) ||
+               pg_add_size_overflow(tot, fs_len, &tot) ||
+               pg_add_size_overflow(tot, 2, &tot))
                goto overflow;
        }
-       if (add_size_overflow(tot, 1, &tot))    /* terminator */
+       if (pg_add_size_overflow(tot, 1, &tot)) /* terminator */
            goto overflow;
 
        border = malloc(tot);

diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 838e42e661a9f4d243c3e24cee7217b390122559..16f504a867d8672be729df9731a9b4f70a548c36 100644 (file)
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -25,6 +25,7 @@
 #include <netinet/tcp.h>
 #endif
 
+#include "common/int.h"
 #include "libpq-fe.h"
 #include "libpq-int.h"
 #include "mb/pg_wchar.h"
@@ -2404,26 +2405,6 @@ pqBuildStartupPacket3(PGconn *conn, int *packetlen,
    return startpacket;
 }
 
-/*
- * Frontend version of the backend's add_size(), intended to be API-compatible
- * with the pg_add_*_overflow() helpers. Stores the result into *dst on success.
- * Returns true instead if the addition overflows.
- *
- * TODO: move to common/int.h
- */
-static bool
-add_size_overflow(size_t s1, size_t s2, size_t *dst)
-{
-   size_t      result;
-
-   result = s1 + s2;
-   if (result < s1 || result < s2)
-       return true;
-
-   *dst = result;
-   return false;
-}
-
 /*
  * Build a startup packet given a filled-in PGconn structure.
  *
@@ -2456,11 +2437,11 @@ build_startup_packet(const PGconn *conn, char *packet,
    do { \
        if (packet) \
            strcpy(packet + packet_len, optname); \
-       if (add_size_overflow(packet_len, strlen(optname) + 1, &packet_len)) \
+       if (pg_add_size_overflow(packet_len, strlen(optname) + 1, &packet_len)) \
            return 0; \
        if (packet) \
            strcpy(packet + packet_len, optval); \
-       if (add_size_overflow(packet_len, strlen(optval) + 1, &packet_len)) \
+       if (pg_add_size_overflow(packet_len, strlen(optval) + 1, &packet_len)) \
            return 0; \
    } while(0)
 
@@ -2496,7 +2477,7 @@ build_startup_packet(const PGconn *conn, char *packet,
    /* Add trailing terminator */
    if (packet)
        packet[packet_len] = '\0';
-   if (add_size_overflow(packet_len, 1, &packet_len))
+   if (pg_add_size_overflow(packet_len, 1, &packet_len))
        return 0;
 
    return packet_len;