1 files changed, 107 insertions, 0 deletions
diff --git a/src/libcamera/base/backtrace.cpp b/src/libcamera/base/backtrace.cpp
new file mode 100644
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+++ b/src/libcamera/base/backtrace.cpp
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+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Ideas on Board Oy
+ *
+ * backtrace.h - Call stack backtraces
+ */
+
+#include <libcamera/base/backtrace.h>
+
+#if HAVE_BACKTRACE
+#include <execinfo.h>
+#include <stdlib.h>
+#endif
+
+#include <sstream>
+
+#include <libcamera/base/span.h>
+
+/**
+ * \file backtrace.h
+ * \brief Generate call stack backtraces
+ */
+
+namespace libcamera {
+
+/**
+ * \class Backtrace
+ * \brief Representation of a call stack backtrace
+ *
+ * The Backtrace class represents a function call stack. Constructing an
+ * instance captures the call stack at the point the instance is constructed.
+ * The instance can later be used to access the call stack and to generate a
+ * human-readable representation with the toString() function.
+ *
+ * Depending on the platform, different backends can be used to generate the
+ * backtrace. The Backtrace class provides a best effort to capture accurate
+ * backtraces, but doesn't offer any guarantee of a particular backtrace format.
+ */
+
+/**
+ * \brief Construct a backtrace
+ *
+ * The backtrace captures the call stack at the point where it is constructed.
+ * It can later be converted to a string with toString().
+ */
+Backtrace::Backtrace()
+{
+#if HAVE_BACKTRACE
+	backtrace_.resize(32);
+
+	int num_entries = backtrace(backtrace_.data(), backtrace_.size());
+	if (num_entries < 0) {
+		backtrace_.clear();
+		return;
+	}
+
+	backtrace_.resize(num_entries);
+#endif
+}
+
+/**
+ * \brief Convert a backtrace to a string representation
+ * \param[in] skipLevels Number of initial levels to skip in the backtrace
+ *
+ * The string representation of the backtrace is a multi-line string, with one
+ * line per call stack entry. The format of the entries isn't specified and is
+ * platform-dependent.
+ *
+ * The \a skipLevels parameter indicates how many initial entries to skip from
+ * the backtrace. This can be used to hide functions that wrap the construction
+ * of the Backtrace instance from the call stack. The Backtrace constructor
+ * itself is automatically skipped and never shown in the backtrace.
+ *
+ * If backtrace generation fails for any reason (usually because the platform
+ * doesn't support this feature), an empty string is returned.
+ *
+ * \return A string representation of the backtrace, or an empty string if
+ * backtrace generation isn't possible
+ */
+std::string Backtrace::toString(unsigned int skipLevels) const
+{
+	/* Skip the first entry, corresponding to the Backtrace construction. */
+	skipLevels += 1;
+
+	if (backtrace_.size() <= skipLevels)
+		return std::string();
+
+#if HAVE_BACKTRACE
+	Span<void *const> trace{ backtrace_ };
+	trace = trace.subspan(skipLevels);
+
+	char **strings = backtrace_symbols(trace.data(), trace.size());
+	if (strings) {
+		std::ostringstream msg;
+
+		for (unsigned int i = 0; i < trace.size(); ++i)
+			msg << strings[i] << std::endl;
+
+		free(strings);
+		return msg.str();
+	}
+#endif
+
+	return std::string();
+}
+
+} /* namespace libcamera */