Fix TestLinuxRVV test fail

Fail log:
[ RUN      ] LibYUVBaseTest.TestLinuxRVV
Note: testing to load "../../unit_test/testdata/riscv64.txt"
/scratch/brucel/libyuv/src/unit_test/cpu_test.cc:290: Failure
Expected equality of these values:
  kCpuHasRVV | kCpuHasRVVZVFH
    Which is: 1610612736
  RiscvCpuCaps("../../unit_test/testdata/riscv64_rvv_zvfh.txt")
    Which is: 536870912
[  FAILED  ] LibYUVBaseTest.TestLinuxRVV (17 ms)

Reason:
The root cause is "\n"  may be contained in the ext variable.
The last of extension substring contains "\n".
For instance, test case riscv64_rvv_zvfh.txt, the last substring is "zvfh\n" instead of "zvfh".
Solved this failure by removing "\n" which is at the end of line.

NOTE: We avoid using strstr() to solve the problem here.
Becasue using strstr() will violate the parsing rule, if future extension contains "zvfh"(e.g zvfhxxx).

Log after modification:
[ RUN      ] LibYUVBaseTest.TestLinuxRVV
Note: testing to load "../../unit_test/testdata/riscv64.txt"
[       OK ] LibYUVBaseTest.TestLinuxRVV (38 ms)

Change-Id: I7b7db98dbc5388cbc148423da6892b8f0be64599
Signed-off-by: Bruce Lai <bruce.lai@sifive.com>
Reviewed-on: https://chromium-review.googlesource.com/c/libyuv/libyuv/+/4498101
Reviewed-by: Frank Barchard <fbarchard@chromium.org>
Commit-Queue: Frank Barchard <fbarchard@chromium.org>

1 files changed, 13 insertions, 8 deletions

diff --git a/source/cpu_id.cc b/source/cpu_id.cc
index 61de60f3..0c4a1581 100644
--- a/source/cpu_id.cc
+++ b/source/cpu_id.cc
@@ -181,26 +181,31 @@ LIBYUV_API SAFEBUFFERS int RiscvCpuCaps(const char* cpuinfo_name) {
       // ISA string must begin with rv64{i,e,g} for a 64-bit processor.
       char* isa = strstr(cpuinfo_line, "rv64");
       if (isa) {
-        const int isa_len = strlen(isa);
-        // 5 ISA characters + 1 new-line character
-        if (isa_len < 6) {
+        size_t isa_len = strlen(isa);
+        char* extensions;
+        size_t extensions_len = 0;
+        size_t std_isa_len;
+        // Remove the new-line character at the end of string
+        if (isa[isa_len - 1] == '\n') {
+          isa[--isa_len] = '\0';
+        }
+        // 5 ISA characters
+        if (isa_len < 5) {
           fclose(f);
           return 0;
         }
         // Skip {i,e,g} canonical checking.
         // Skip rvxxx
         isa += 5;
-
         // Find the very first occurrence of 's', 'x' or 'z'.
         // To detect multi-letter standard, non-standard, and
         // supervisor-level extensions.
-        int extensions_len = 0;
-        char* extensions = strpbrk(isa, "zxs");
+        extensions = strpbrk(isa, "zxs");
         if (extensions) {
-          extensions_len = strlen(extensions);
           // Multi-letter extensions are seperated by a single underscore
           // as described in RISC-V User-Level ISA V2.2.
           char* ext = strtok(extensions, "_");
+          extensions_len = strlen(extensions);
           while (ext) {
             // Search for the ZVFH (Vector FP16) extension.
             if (!strcmp(ext, "zvfh")) {
@@ -209,7 +214,7 @@ LIBYUV_API SAFEBUFFERS int RiscvCpuCaps(const char* cpuinfo_name) {
             ext = strtok(NULL, "_");
           }
         }
-        const int std_isa_len = isa_len - extensions_len - 5 - 1;
+        std_isa_len = isa_len - extensions_len - 5;
         // Detect the v in the standard single-letter extensions.
         if (memchr(isa, 'v', std_isa_len)) {
           // The RVV implied the F extension.