diff: clarify textconv interface
The memory allocation scheme for the textconv interface is a bit tricky, and not well documented. It was originally designed as an internal part of diff.c (matching fill_mmfile), but gradually was made public. Refactoring it is difficult, but we can at least improve the situation by documenting the intended flow and enforcing it with an in-code assertion. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jeff King committed
Feb 22, 2016 at 13:28 UTC
a64e6a44c63a965c5bc26242ddd3ed049b42e117
3 files changed
+24
-1
diff.c
+4
-1
@@ -4996,7 +4996,7 @@ size_t fill_textconv(struct userdiff_driver *driver,
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{
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size_t size;
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- if (!driver || !driver->textconv) {
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+ if (!driver) {
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if (!DIFF_FILE_VALID(df)) {
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*outbuf = "";
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return 0;
@@ -5007,6 +5007,9 @@ size_t fill_textconv(struct userdiff_driver *driver,
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return df->size;
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}
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+ if (!driver->textconv)
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+ die("BUG: fill_textconv called with non-textconv driver");
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+
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if (driver->textconv_cache && df->sha1_valid) {
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*outbuf = notes_cache_get(driver->textconv_cache, df->sha1,
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&size);
diff.h
+16
@@ -342,10 +342,26 @@ extern void diff_no_index(struct rev_info *, int, const char **, const char *);
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extern int index_differs_from(const char *def, int diff_flags);
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+/*
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+ * Fill the contents of the filespec "df", respecting any textconv defined by
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+ * its userdiff driver. The "driver" parameter must come from a
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+ * previous call to get_textconv(), and therefore should either be NULL or have
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+ * textconv enabled.
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+ *
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+ * Note that the memory ownership of the resulting buffer depends on whether
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+ * the driver field is NULL. If it is, then the memory belongs to the filespec
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+ * struct. If it is non-NULL, then "outbuf" points to a newly allocated buffer
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+ * that should be freed by the caller.
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+ */
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extern size_t fill_textconv(struct userdiff_driver *driver,
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struct diff_filespec *df,
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char **outbuf);
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+/*
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+ * Look up the userdiff driver for the given filespec, and return it if
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+ * and only if it has textconv enabled (otherwise return NULL). The result
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+ * can be passed to fill_textconv().
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+ */
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extern struct userdiff_driver *get_textconv(struct diff_filespec *one);
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extern int parse_rename_score(const char **cp_p);
userdiff.h
+4
@@ -23,6 +23,10 @@ int userdiff_config(const char *k, const char *v);
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struct userdiff_driver *userdiff_find_by_name(const char *name);
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struct userdiff_driver *userdiff_find_by_path(const char *path);
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+/*
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+ * Initialize any textconv-related fields in the driver and return it, or NULL
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+ * if it does not have textconv enabled at all.
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+ */
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struct userdiff_driver *userdiff_get_textconv(struct userdiff_driver *driver);
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#endif /* USERDIFF */