Fix strncasecmp bounds and alpha-only case folding

+ Added unit tests for string.c

Author: danielinux

src/string.c

@@ -117,14 +117,20 @@ int strcmp(const char *s1, const char *s2)
 }
 #endif /* Renesas CCRX */
 
+static int is_alpha(int c)
+{
+    return ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'));
+}
+
 int strcasecmp(const char *s1, const char *s2)
 {
     int diff = 0;
 
     while (!diff && *s1) {
         diff = (int)*s1 - (int)*s2;
 
-        if ((diff == 'A' - 'a') || (diff == 'a' - 'A'))
+        if (((diff == 'A' - 'a') || (diff == 'a' - 'A')) &&
+                (is_alpha((unsigned char)*s1) || is_alpha((unsigned char)*s2)))
             diff = 0;
 
         s1++;
@@ -142,12 +148,13 @@ int strncasecmp(const char *s1, const char *s2, size_t n)
     while (!diff && *s1) {
         diff = (int)*s1 - (int)*s2;
 
-        if ((diff == 'A' - 'a') || (diff == 'a' - 'A'))
+        if (((diff == 'A' - 'a') || (diff == 'a' - 'A')) &&
+                (is_alpha((unsigned char)*s1) || is_alpha((unsigned char)*s2)))
             diff = 0;
 
         s1++;
         s2++;
-        if (++i > n)
+        if (++i >= n)
             break;
     }
     return diff;

tools/unit-tests/Makefile

@@ -25,10 +25,11 @@ LDFLAGS+=-ftest-coverage
 
 
 
-TESTS:=unit-parser unit-extflash unit-spi-flash unit-aes128 unit-aes256 \
-       unit-chacha20 unit-pci unit-mock-state unit-sectorflags unit-image \
-       unit-nvm unit-nvm-flagshome unit-enc-nvm unit-enc-nvm-flagshome \
-       unit-delta unit-update-flash unit-update-ram unit-pkcs11_store
+TESTS:=unit-parser unit-extflash unit-string unit-spi-flash unit-aes128 \
+       unit-aes256 unit-chacha20 unit-pci unit-mock-state unit-sectorflags \
+       unit-image unit-nvm unit-nvm-flagshome unit-enc-nvm \
+       unit-enc-nvm-flagshome unit-delta unit-update-flash unit-update-ram \
+       unit-pkcs11_store
 
 all: $(TESTS)
 
@@ -94,6 +95,9 @@ unit-extflash: ../../include/target.h unit-extflash.c
 unit-spi-flash: ../../include/target.h unit-spi-flash.c
 	gcc -o $@ $^ $(CFLAGS) $(LDFLAGS)
 
+unit-string: ../../include/target.h unit-string.c
+	gcc -o $@ $^ $(CFLAGS) -DDEBUG_UART -DPRINTF_ENABLED $(LDFLAGS)
+
 unit-aes128: ../../include/target.h unit-extflash.c
 	gcc -o $@ $^ $(CFLAGS) $(LDFLAGS)