pack: Fix signed unpacking to not modify the input.

[upkg.git] / src / pack.c

diff --git a/src/pack.c b/src/pack.c
index e711de19dcb50722d0f5a3e1362c45f31eff1de0..9f4998f12f9050fa22d32a34f688a217531e6083 100644 (file)
--- a/src/pack.c
+++ b/src/pack.c
@@ -56,7 +56,7 @@ DEFPACK_LE(64, unsigned long long)
 #endif
 
 #define DEFUNPACK_BE(bits, type) type unpack_ ## bits ## _be ( \
-       unsigned char *in \
+       const unsigned char *in \
 ) { \
        type v = 0; \
        unsigned i; \
@@ -68,7 +68,7 @@ DEFPACK_LE(64, unsigned long long)
 }
 
 #define DEFUNPACK_LE(bits, type) type unpack_ ## bits ## _le ( \
-       unsigned char *in \
+       const unsigned char *in \
 ) { \
        type v = 0; \
        unsigned i; \
@@ -97,29 +97,27 @@ DEFUNPACK_LE(64, unsigned long long)
  */
 
 #define DEFUNPACK_SBE(bits, max, type) type unpack_s ## bits ## _be ( \
-       unsigned char *in \
+       const unsigned char *in \
 ) { \
        type v = 0; \
        unsigned i; \
        int sign = (in[0] & 0x80) ? 1 : 0; \
-       in[0] &= 0x7f; \
        for (i = 0; i < bits/8; i++) { \
                v *= 256; \
-               v += in[i]; \
+               v += in[i] & (i == 0 ? 0x7f : 0xff); \
        } \
        return sign*(-max-1) + v; \
 }
 
 #define DEFUNPACK_SLE(bits, max, type) type unpack_s ## bits ## _le ( \
-       unsigned char *in \
+       const unsigned char *in \
 ) { \
        type v = 0; \
        unsigned i; \
        int sign = (in[bits/8 - 1] & 0x80) ? 1 : 0; \
-       in[bits/8 - 1] &= 0x7f; \
        for (i = 1; i <= bits/8; i++) { \
                v *= 256; \
-               v += in[bits/8 - i]; \
+               v += in[bits/8 - i] & (i == 1 ? 0x7f : 0xff); \
        } \
        return sign*(-max-1) + v; \
 }