Make sure logs are always ended with newline

native/src/base/compat/compat.cpp

@@ -146,6 +146,8 @@ int sigemptyset(sigset_t *set) {
     return 0;
 }
 
+#undef vsnprintf
+#undef snprintf
 #include "fortify.hpp"
 
 #endif

native/src/base/files.cpp

@@ -10,7 +10,7 @@
 using namespace std;
 
 ssize_t fd_path(int fd, char *path, size_t size) {
-    snprintf(path, size, "/proc/self/fd/%d", fd);
+    ssprintf(path, size, "/proc/self/fd/%d", fd);
     return xreadlink(path, path, size);
 }
 

native/src/base/logging.cpp

@@ -13,7 +13,7 @@ using namespace std;
 
 static int fmt_and_log_with_rs(LogLevel level, const char *fmt, va_list ap) {
     char buf[4096];
-    int ret = vsnprintf(buf, sizeof(buf), fmt, ap);
+    int ret = vssprintf(buf, sizeof(buf), fmt, ap);
     log_with_rs(level, rust::Str(buf, ret));
     return ret;
 }
@@ -41,10 +41,15 @@ extern "C" int magisk_log_print(int prio, const char *tag, const char *fmt, ...)
     }
 
     char fmt_buf[4096];
-    auto len = strlcpy(fmt_buf, tag, sizeof(fmt_buf));
+    auto len = strlcpy(fmt_buf, tag, sizeof(fmt_buf) - 1);
     // Prevent format specifications in the tag
     std::replace(fmt_buf, fmt_buf + len, '%', '_');
-    snprintf(fmt_buf + len, sizeof(fmt_buf) - len, ": %s", fmt);
+    len = ssprintf(fmt_buf + len, sizeof(fmt_buf) - len - 1, ": %s", fmt) + len;
+    // Ensure the fmt string always ends with newline
+    if (fmt_buf[len - 1] != '\n') {
+        fmt_buf[len] = '\n';
+        fmt_buf[len + 1] = '\0';
+    }
     va_list argv;
     va_start(argv, fmt);
     int ret = cpp_logger(level, fmt_buf, argv);

native/src/base/misc.cpp

@@ -168,7 +168,7 @@ uint32_t binary_gcd(uint32_t u, uint32_t v) {
 
 int switch_mnt_ns(int pid) {
     char mnt[32];
-    snprintf(mnt, sizeof(mnt), "/proc/%d/ns/mnt", pid);
+    ssprintf(mnt, sizeof(mnt), "/proc/%d/ns/mnt", pid);
     if (access(mnt, R_OK) == -1) return 1; // Maybe process died..
 
     int fd, ret;
@@ -211,3 +211,16 @@ vector<string> split(const string &s, const string &delims) {
 vector<string_view> split_ro(string_view s, string_view delims) {
     return split_impl<string_view>(s, delims);
 }
+
+#undef vsnprintf
+int vssprintf(char *dest, size_t size, const char *fmt, va_list ap) {
+    return std::min(vsnprintf(dest, size, fmt, ap), (int) size - 1);
+}
+
+int ssprintf(char *dest, size_t size, const char *fmt, ...) {
+    va_list va;
+    va_start(va, fmt);
+    int r = vssprintf(dest, size, fmt, va);
+    va_end(va);
+    return r;
+}

native/src/base/misc.hpp

@@ -156,6 +156,15 @@ std::string &replace_all(std::string &str, std::string_view from, std::string_vi
 std::vector<std::string> split(const std::string &s, const std::string &delims);
 std::vector<std::string_view> split_ro(std::string_view, std::string_view delims);
 
+// Similar to vsnprintf, but the return value is the written number of bytes
+int vssprintf(char *dest, size_t size, const char *fmt, va_list ap);
+// Similar to snprintf, but the return value is the written number of bytes
+int ssprintf(char *dest, size_t size, const char *fmt, ...);
+
+// Ban usage of unsafe cstring functions
+#define vsnprintf  __use_vssprintf_instead__
+#define snprintf   __use_ssprintf_instead__
+
 struct exec_t {
     bool err = false;
     int fd = -2;