#include <unistd.h>
#include <common/common.h>
+#include <common/readwrite.h>
#include <common/runas.h>
#include <common/compat/getenv.h>
#include <common/compat/string.h>
#include "defaults.h"
#include "time.h"
+#define PROC_MEMINFO_PATH "/proc/meminfo"
+#define PROC_MEMINFO_MEMAVAILABLE_LINE "MemAvailable:"
+#define PROC_MEMINFO_MEMTOTAL_LINE "MemTotal:"
+
+/* The length of the longest field of `/proc/meminfo`. */
+#define PROC_MEMINFO_FIELD_MAX_NAME_LEN 20
+
+#if (PROC_MEMINFO_FIELD_MAX_NAME_LEN == 20)
+#define MAX_NAME_LEN_SCANF_IS_A_BROKEN_API "19"
+#else
+#error MAX_NAME_LEN_SCANF_IS_A_BROKEN_API must be updated to match (PROC_MEMINFO_FIELD_MAX_NAME_LEN - 1)
+#endif
+
/*
* Return a partial realpath(3) of the path even if the full path does not
* exist. For instance, with /tmp/test1/test2/test3, if test2/ does not exist
end:
return ret;
}
+
+static
+int read_proc_meminfo_field(const char *field, size_t *value)
+{
+ int ret;
+ FILE *proc_meminfo;
+ char name[PROC_MEMINFO_FIELD_MAX_NAME_LEN] = {};
+
+ proc_meminfo = fopen(PROC_MEMINFO_PATH, "r");
+ if (!proc_meminfo) {
+ PERROR("Failed to fopen() " PROC_MEMINFO_PATH);
+ ret = -1;
+ goto fopen_error;
+ }
+
+ /*
+ * Read the contents of /proc/meminfo line by line to find the right
+ * field.
+ */
+ while (!feof(proc_meminfo)) {
+ unsigned long value_kb;
+
+ ret = fscanf(proc_meminfo,
+ "%" MAX_NAME_LEN_SCANF_IS_A_BROKEN_API "s %lu kB\n",
+ name, &value_kb);
+ if (ret == EOF) {
+ /*
+ * fscanf() returning EOF can indicate EOF or an error.
+ */
+ if (ferror(proc_meminfo)) {
+ PERROR("Failed to parse " PROC_MEMINFO_PATH);
+ }
+ break;
+ }
+
+ if (ret == 2 && strcmp(name, field) == 0) {
+ /*
+ * This number is displayed in kilo-bytes. Return the
+ * number of bytes.
+ */
+ *value = ((size_t) value_kb) * 1024;
+ ret = 0;
+ goto found;
+ }
+ }
+ /* Reached the end of the file without finding the right field. */
+ ret = -1;
+
+found:
+ fclose(proc_meminfo);
+fopen_error:
+ return ret;
+}
+
+/*
+ * Returns an estimate of the number of bytes of memory available based on the
+ * the information in `/proc/meminfo`. The number returned by this function is
+ * a best guess.
+ */
+LTTNG_HIDDEN
+int utils_get_memory_available(size_t *value)
+{
+ return read_proc_meminfo_field(PROC_MEMINFO_MEMAVAILABLE_LINE, value);
+}
+
+/*
+ * Returns the total size of the memory on the system in bytes based on the
+ * the information in `/proc/meminfo`.
+ */
+LTTNG_HIDDEN
+int utils_get_memory_total(size_t *value)
+{
+ return read_proc_meminfo_field(PROC_MEMINFO_MEMTOTAL_LINE, value);
+}