diff options
author | Berthold Stoeger <bstoeger@mail.tuwien.ac.at> | 2021-07-20 07:24:07 +0200 |
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committer | Dirk Hohndel <dirk@hohndel.org> | 2021-07-23 11:22:43 -0700 |
commit | f142e9a9c6ba493c09a282544da8715b3656648e (patch) | |
tree | 8b419cad550f086022acdc175a7cc7dd65e7f1e2 /core | |
parent | 0c84f369c35bf416071b9ef6d5a401b457fd4a38 (diff) | |
download | subsurface-f142e9a9c6ba493c09a282544da8715b3656648e.tar.gz |
core: C++-ify membuffer
C-style memory management is a pain and nearly nobody seems to get
it right. Add a C++-version of membuffer that frees the buffer
when it gets out-of-scope. Originally, I was thinking about
conditionally adding a constructor/destructor pair when compiling
with C++. But then decided to create a derived class membufferpp,
because it would be extremely confusing to have behavioral change
when changing a source from from C to C++ or vice-versa.
Also add a comment about the dangers of returned pointer: They
become dangling on changes to the membuffer.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Diffstat (limited to 'core')
-rw-r--r-- | core/CMakeLists.txt | 2 | ||||
-rw-r--r-- | core/format.cpp | 2 | ||||
-rw-r--r-- | core/membuffer.cpp (renamed from core/membuffer.c) | 12 | ||||
-rw-r--r-- | core/membuffer.h | 17 |
4 files changed, 25 insertions, 8 deletions
diff --git a/core/CMakeLists.txt b/core/CMakeLists.txt index c2103ab71..5b356e53f 100644 --- a/core/CMakeLists.txt +++ b/core/CMakeLists.txt @@ -122,7 +122,7 @@ set(SUBSURFACE_CORE_LIB_SRCS libdivecomputer.h liquivision.c load-git.c - membuffer.c + membuffer.cpp membuffer.h metadata.cpp metadata.h diff --git a/core/format.cpp b/core/format.cpp index a540f4c21..3da97293a 100644 --- a/core/format.cpp +++ b/core/format.cpp @@ -397,7 +397,6 @@ int vasprintf_loc(char **dst, const char *cformat, va_list ap) return utf8.size(); } -// This function is defined here instead of membuffer.c, because it needs to access QString. extern "C" void put_vformat_loc(struct membuffer *b, const char *fmt, va_list args) { QByteArray utf8 = vqasprintf_loc(fmt, args).toUtf8(); @@ -408,4 +407,3 @@ extern "C" void put_vformat_loc(struct membuffer *b, const char *fmt, va_list ar memcpy(b->buffer + b->len, data, utf8_size); b->len += utf8_size; } - diff --git a/core/membuffer.c b/core/membuffer.cpp index 3b42797e1..2c0af9f0d 100644 --- a/core/membuffer.c +++ b/core/membuffer.cpp @@ -12,6 +12,16 @@ #include "units.h" #include "membuffer.h" +membufferpp::membufferpp() + : membuffer{0, 0, nullptr} +{ +} + +membufferpp::~membufferpp() +{ + free_buffer(this); +} + /* Only for internal use */ static char *detach_buffer(struct membuffer *b) { @@ -66,7 +76,7 @@ void make_room(struct membuffer *b, unsigned int size) char *n; /* round it up to not reallocate all the time.. */ needed = needed * 9 / 8 + 1024; - n = realloc(b->buffer, needed); + n = (char *)realloc(b->buffer, needed); if (!n) oom(); b->buffer = n; diff --git a/core/membuffer.h b/core/membuffer.h index 6d497371c..821b0cecb 100644 --- a/core/membuffer.h +++ b/core/membuffer.h @@ -36,10 +36,6 @@ #ifndef MEMBUFFER_H #define MEMBUFFER_H -#ifdef __cplusplus -extern "C" { -#endif - #include <ctype.h> #include <stdio.h> #include <stdarg.h> @@ -50,6 +46,17 @@ struct membuffer { char *buffer; }; +#ifdef __cplusplus + +// In C++ code use this - it automatically frees the buffer, when going out of scope. +struct membufferpp : public membuffer { + membufferpp(); + ~membufferpp(); +}; + +extern "C" { +#endif + #ifdef __GNUC__ #define __printf(x, y) __attribute__((__format__(__printf__, x, y))) #else @@ -64,6 +71,8 @@ extern void put_bytes(struct membuffer *, const char *, int); extern void put_string(struct membuffer *, const char *); extern void put_quoted(struct membuffer *, const char *, int, int); extern void strip_mb(struct membuffer *); + +/* The pointer obtained by mb_cstring is invalidated by any modifictation to the membuffer! */ extern const char *mb_cstring(struct membuffer *); extern __printf(2, 0) void put_vformat(struct membuffer *, const char *, va_list); extern __printf(2, 0) void put_vformat_loc(struct membuffer *, const char *, va_list); |