[libvirt] [PATCH v3 4/5] util: Improve CPU frequency parsing
Make the parser both more strict, by not ignoring errors reported
by virStrToLong_ui(), and more permissive, by not failing due to
unrelated fields which just happen to have a know prefix and
accepting any amount of whitespace before the numeric value.
Signed-off-by: Andrea Bolognani <abologna(a)redhat.com>
---
src/util/virhostcpu.c | 62 +++++++++++++++++++++----
tests/virhostcpudata/linux-x86_64-test1.cpuinfo | 4 ++
2 files changed, 57 insertions(+), 9 deletions(-)
diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
index 3c20755eb..9c9f362de 100644
--- a/src/util/virhostcpu.c
+++ b/src/util/virhostcpu.c
@@ -508,6 +508,27 @@ virHostCPUHasValidSubcoreConfiguration(int threads_per_subcore)
return ret;
}
+/**
+ * virHostCPUParseFrequencyString:
+ * @str: string to be parsed
+ * @prefix: expected prefix
+ * @mhz: output location
+ *
+ * Parse a /proc/cpuinfo line and extract the CPU frequency, if present.
+ *
+ * The expected format of @str looks like
+ *
+ * cpu MHz : 2100.000
+ *
+ * where @prefix ("cpu MHz" in the example), is architecture-dependent.
+ *
+ * The decimal part of the CPU frequency, as well as all whitespace, is
+ * ignored.
+ *
+ * Returns: 0 when the string has been parsed successfully and the CPU
+ * frequency has been stored in @mhz, >0 when the string has not
+ * been parsed but no error has occurred, <0 on failure.
+ */
static int
virHostCPUParseFrequencyString(const char *str,
const char *prefix,
@@ -516,26 +537,49 @@ virHostCPUParseFrequencyString(const char *str,
char *p;
unsigned int ui;
+ /* If the string doesn't start with the expected prefix, then
+ * we're not looking at the right string and we should move on */
if (!STRPREFIX(str, prefix))
return 1;
+ /* Skip the prefix */
str += strlen(prefix);
- while (*str && c_isspace(*str))
+ /* Skip all whitespace */
+ while (c_isspace(*str))
str++;
+ if (*str == '\0')
+ goto error;
- if (*str != ':' || !str[1]) {
- virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
- _("parsing cpu MHz from cpuinfo"));
- return -1;
+ /* Skip the colon. If anything but a colon is found, then we're
+ * not looking at the right string and we should move on */
+ if (*str != ':')
+ return 1;
+ str++;
+
+ /* Skip all whitespace */
+ while (c_isspace(*str))
+ str++;
+ if (*str == '\0')
+ goto error;
+
+ /* Parse the frequency. We expect an unsigned value, optionally
+ * followed by a fractional part (which gets discarded) or some
+ * leading whitespace */
+ if (virStrToLong_ui(str, &p, 10, &ui) < 0 ||
+ (*p != '.' && *p != '\0' && !c_isspace(*p))) {
+ goto error;
}
- if (virStrToLong_ui(str + 1, &p, 10, &ui) == 0 &&
- /* Accept trailing fractional part. */
- (*p == '\0' || *p == '.' || c_isspace(*p)))
- *mhz = ui;
+ *mhz = ui;
return 0;
+
+ error:
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Missing or invalid CPU frequency in %s"),
+ CPUINFO_PATH);
+ return -1;
}
static int
diff --git a/tests/virhostcpudata/linux-x86_64-test1.cpuinfo
b/tests/virhostcpudata/linux-x86_64-test1.cpuinfo
index e88a48ff3..706b69a54 100644
--- a/tests/virhostcpudata/linux-x86_64-test1.cpuinfo
+++ b/tests/virhostcpudata/linux-x86_64-test1.cpuinfo
@@ -28,6 +28,10 @@ model : 4
model name : Intel(R) Xeon(TM) CPU 2.80GHz
stepping : 8
cpu MHz : 2800.000
+# The following field is a made-up one, intended to make sure our cpuinfo
+# parser deals correctly with the introduction of new fields that just so
+# happen to share a prefix with the one used for CPU frequency
+cpu MHz rounded up to GHz : 3000.000
cache size : 2048 KB
physical id : 0
siblings : 2
--
2.14.3