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[lttng-tools.git] / src / common / random.cpp

diff --git a/src/common/random.cpp b/src/common/random.cpp
index b5669d097d93f95477a9598e70d5aadfa1cf08e4..ba9d937ba32b95f43f877348ac0f358ea9c7e071 100644 (file)
--- a/src/common/random.cpp
+++ b/src/common/random.cpp
@@ -5,8 +5,7 @@
  *
  */
 
-#include <lttng/constant.h>
-
+#include <common/error.hpp>
 #include <common/file-descriptor.hpp>
 #include <common/format.hpp>
 #include <common/hashtable/utils.hpp>
@@ -14,6 +13,8 @@
 #include <common/readwrite.hpp>
 #include <common/time.hpp>
 
+#include <lttng/constant.h>
+
 #include <fcntl.h>
 
 #ifdef HAVE_SYS_SYSCALL_H
@@ -66,16 +67,27 @@ void getrandom_nonblock(char *out_data, std::size_t size)
 
        if (ret < 0) {
                LTTNG_THROW_POSIX(
-                               fmt::format("Failed to get true random data using getrandom(): size={}",
-                                               size),
-                               errno);
+                       lttng::format("Failed to get true random data using getrandom(): size={}",
+                                     size),
+                       errno);
        }
 }
-#else /* defined(__linux__) && defined(SYS_getrandom) && defined(HAVE_SYS_RANDOM_H) */
+#elif defined(HAVE_ARC4RANDOM)
+
+#include <stdlib.h>
+
+/*
+ * According to the MacOS / FreeBSD manpage, this function never fails nor blocks.
+ */
 void getrandom_nonblock(char *out_data, std::size_t size)
 {
-       LTTNG_THROW_RANDOM_PRODUCTION_ERROR(
-                       "getrandom() is not supported by this platform");
+       arc4random_buf(out_data, size);
+}
+#else /* defined(__linux__) && defined(SYS_getrandom) && defined(HAVE_SYS_RANDOM_H) */
+__attribute__((noreturn)) void getrandom_nonblock(char *out_data __attribute__((unused)),
+                                                 std::size_t size __attribute__((unused)))
+{
+       LTTNG_THROW_RANDOM_PRODUCTION_ERROR("getrandom() is not supported by this platform");
 }
 #endif /* defined(__linux__) && defined(SYS_getrandom) && defined(HAVE_SYS_RANDOM_H) */
 
@@ -91,25 +103,23 @@ lttng::random::seed_t produce_pseudo_random_seed()
        ret = clock_gettime(CLOCK_REALTIME, &real_time);
        if (ret) {
                LTTNG_THROW_POSIX("Failed to read real time while generating pseudo-random seed",
-                               errno);
+                                 errno);
        }
 
        ret = clock_gettime(CLOCK_MONOTONIC, &monotonic_time);
        if (ret) {
                LTTNG_THROW_POSIX(
-                               "Failed to read monotonic time while generating pseudo-random seed",
-                               errno);
+                       "Failed to read monotonic time while generating pseudo-random seed", errno);
        }
 
        ret = gethostname(hostname, sizeof(hostname));
        if (ret) {
                LTTNG_THROW_POSIX("Failed to get host name while generating pseudo-random seed",
-                               errno);
+                                 errno);
        }
 
        hash_seed = (unsigned long) real_time.tv_nsec ^ (unsigned long) real_time.tv_sec ^
-                       (unsigned long) monotonic_time.tv_nsec ^
-                       (unsigned long) monotonic_time.tv_sec;
+               (unsigned long) monotonic_time.tv_nsec ^ (unsigned long) monotonic_time.tv_sec;
        seed = hash_key_ulong((void *) real_time.tv_sec, hash_seed);
        seed ^= hash_key_ulong((void *) real_time.tv_nsec, hash_seed);
        seed ^= hash_key_ulong((void *) monotonic_time.tv_sec, hash_seed);
@@ -128,7 +138,7 @@ lttng::random::seed_t produce_random_seed_from_urandom()
         * Open /dev/urandom as a file_descriptor, or throw on error. The
         * lambda is used to reduce the scope of the raw fd as much as possible.
         */
-       lttng::file_descriptor urandom{[]() {
+       lttng::file_descriptor urandom{ []() {
                const auto urandom_raw_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
 
                if (urandom_raw_fd < 0) {
@@ -136,14 +146,14 @@ lttng::random::seed_t produce_random_seed_from_urandom()
                }
 
                return urandom_raw_fd;
-       }()};
+       }() };
 
        lttng::random::seed_t seed;
-       const auto read_ret = lttng_read(urandom.fd(), &seed, sizeof(seed));
-       if (read_ret != sizeof(seed)) {
-               LTTNG_THROW_POSIX(fmt::format("Failed to read from `/dev/urandom`: size={}",
-                                                 sizeof(seed)),
-                               errno);
+       try {
+               urandom.read(&seed, sizeof(seed));
+       } catch (const std::exception& e) {
+               LTTNG_THROW_RANDOM_PRODUCTION_ERROR(lttng::format(
+                       "Failed to read from `/dev/urandom`: size={}: {}", sizeof(seed), e.what()));
        }
 
        return seed;
@@ -152,9 +162,9 @@ lttng::random::seed_t produce_random_seed_from_urandom()
 } /* namespace */
 
 lttng::random::production_error::production_error(const std::string& msg,
-               const char *file_name,
-               const char *function_name,
-               unsigned int line_number) :
+                                                 const char *file_name,
+                                                 const char *function_name,
+                                                 unsigned int line_number) :
        lttng::runtime_error(msg, file_name, function_name, line_number)
 {
 }
@@ -171,11 +181,12 @@ lttng::random::seed_t lttng::random::produce_best_effort_random_seed()
 {
        try {
                return lttng::random::produce_true_random_seed();
-       } catch (std::exception& e) {
+       } catch (const std::exception& e) {
                WARN("%s",
-                               fmt::format("Failed to produce a random seed using getrandom(), falling back to pseudo-random device seed generation which will block until its pool is initialized: {}",
-                                               e.what())
-                                               .c_str());
+                    lttng::format(
+                            "Failed to produce a random seed using getrandom(), falling back to pseudo-random device seed generation which will block until its pool is initialized: {}",
+                            e.what())
+                            .c_str());
        }
 
        try {
@@ -184,11 +195,11 @@ lttng::random::seed_t lttng::random::produce_best_effort_random_seed()
                 * under some containerized environments.
                 */
                produce_random_seed_from_urandom();
-       } catch (std::exception& e) {
+       } catch (const std::exception& e) {
                WARN("%s",
-                               fmt::format("Failed to produce a random seed from the urandom device: {}",
-                                               e.what())
-                                               .c_str());
+                    lttng::format("Failed to produce a random seed from the urandom device: {}",
+                                  e.what())
+                            .c_str());
        }
 
        /* Fallback to time-based seed generation. */