diff --git a/strbuf.h b/strbuf.h
index 60a35aef16..bf18fddb5b 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -87,7 +87,7 @@ struct object_id;
  * Initialize the structure. The second parameter can be zero or a bigger
  * number to allocate memory, in case you want to prevent further reallocs.
  */
-extern void strbuf_init(struct strbuf *, size_t);
+void strbuf_init(struct strbuf *sb, size_t alloc);
 
 /**
  * Release a string buffer and the memory it used. After this call, the
@@ -97,7 +97,7 @@ extern void strbuf_init(struct strbuf *, size_t);
  * To clear a strbuf in preparation for further use without the overhead
  * of free()ing and malloc()ing again, use strbuf_reset() instead.
  */
-extern void strbuf_release(struct strbuf *);
+void strbuf_release(struct strbuf *sb);
 
 /**
  * Detach the string from the strbuf and returns it; you now own the
@@ -107,7 +107,7 @@ extern void strbuf_release(struct strbuf *);
  * The strbuf that previously held the string is reset to `STRBUF_INIT` so
  * it can be reused after calling this function.
  */
-extern char *strbuf_detach(struct strbuf *, size_t *);
+char *strbuf_detach(struct strbuf *sb, size_t *sz);
 
 /**
  * Attach a string to a buffer. You should specify the string to attach,
@@ -117,7 +117,7 @@ extern char *strbuf_detach(struct strbuf *, size_t *);
  * malloc()ed, and after attaching, the pointer cannot be relied upon
  * anymore, and neither be free()d directly.
  */
-extern void strbuf_attach(struct strbuf *, void *, size_t, size_t);
+void strbuf_attach(struct strbuf *sb, void *str, size_t len, size_t mem);
 
 /**
  * Swap the contents of two string buffers.
@@ -148,7 +148,7 @@ static inline size_t strbuf_avail(const struct strbuf *sb)
  * This is never a needed operation, but can be critical for performance in
  * some cases.
  */
-extern void strbuf_grow(struct strbuf *, size_t);
+void strbuf_grow(struct strbuf *sb, size_t amount);
 
 /**
  * Set the length of the buffer to a given value. This function does *not*
@@ -183,30 +183,30 @@ static inline void strbuf_setlen(struct strbuf *sb, size_t len)
  * Strip whitespace from the beginning (`ltrim`), end (`rtrim`), or both side
  * (`trim`) of a string.
  */
-extern void strbuf_trim(struct strbuf *);
-extern void strbuf_rtrim(struct strbuf *);
-extern void strbuf_ltrim(struct strbuf *);
+void strbuf_trim(struct strbuf *sb);
+void strbuf_rtrim(struct strbuf *sb);
+void strbuf_ltrim(struct strbuf *sb);
 
 /* Strip trailing directory separators */
-extern void strbuf_trim_trailing_dir_sep(struct strbuf *);
+void strbuf_trim_trailing_dir_sep(struct strbuf *sb);
 
 /**
  * Replace the contents of the strbuf with a reencoded form.  Returns -1
  * on error, 0 on success.
  */
-extern int strbuf_reencode(struct strbuf *sb, const char *from, const char *to);
+int strbuf_reencode(struct strbuf *sb, const char *from, const char *to);
 
 /**
  * Lowercase each character in the buffer using `tolower`.
  */
-extern void strbuf_tolower(struct strbuf *sb);
+void strbuf_tolower(struct strbuf *sb);
 
 /**
  * Compare two buffers. Returns an integer less than, equal to, or greater
  * than zero if the first buffer is found, respectively, to be less than,
  * to match, or be greater than the second buffer.
  */
-extern int strbuf_cmp(const struct strbuf *, const struct strbuf *);
+int strbuf_cmp(const struct strbuf *first, const struct strbuf *second);
 
 
 /**
@@ -233,37 +233,38 @@ static inline void strbuf_addch(struct strbuf *sb, int c)
 /**
  * Add a character the specified number of times to the buffer.
  */
-extern void strbuf_addchars(struct strbuf *sb, int c, size_t n);
+void strbuf_addchars(struct strbuf *sb, int c, size_t n);
 
 /**
  * Insert data to the given position of the buffer. The remaining contents
  * will be shifted, not overwritten.
  */
-extern void strbuf_insert(struct strbuf *, size_t pos, const void *, size_t);
+void strbuf_insert(struct strbuf *sb, size_t pos, const void *, size_t);
 
 /**
  * Remove given amount of data from a given position of the buffer.
  */
-extern void strbuf_remove(struct strbuf *, size_t pos, size_t len);
+void strbuf_remove(struct strbuf *sb, size_t pos, size_t len);
 
 /**
  * Remove the bytes between `pos..pos+len` and replace it with the given
  * data.
  */
-extern void strbuf_splice(struct strbuf *, size_t pos, size_t len,
-			  const void *, size_t);
+void strbuf_splice(struct strbuf *sb, size_t pos, size_t len,
+		   const void *data, size_t data_len);
 
 /**
  * Add a NUL-terminated string to the buffer. Each line will be prepended
  * by a comment character and a blank.
  */
-extern void strbuf_add_commented_lines(struct strbuf *out, const char *buf, size_t size);
+void strbuf_add_commented_lines(struct strbuf *out,
+				const char *buf, size_t size);
 
 
 /**
  * Add data of given length to the buffer.
  */
-extern void strbuf_add(struct strbuf *, const void *, size_t);
+void strbuf_add(struct strbuf *sb, const void *data, size_t len);
 
 /**
  * Add a NUL-terminated string to the buffer.
@@ -282,7 +283,7 @@ static inline void strbuf_addstr(struct strbuf *sb, const char *s)
 /**
  * Copy the contents of another buffer at the end of the current one.
  */
-extern void strbuf_addbuf(struct strbuf *sb, const struct strbuf *sb2);
+void strbuf_addbuf(struct strbuf *sb, const struct strbuf *sb2);
 
 /**
  * This function can be used to expand a format string containing
@@ -308,8 +309,13 @@ extern void strbuf_addbuf(struct strbuf *sb, const struct strbuf *sb2);
  * parameters to the callback, `strbuf_expand()` passes a context pointer,
  * which can be used by the programmer of the callback as she sees fit.
  */
-typedef size_t (*expand_fn_t) (struct strbuf *sb, const char *placeholder, void *context);
-extern void strbuf_expand(struct strbuf *sb, const char *format, expand_fn_t fn, void *context);
+typedef size_t (*expand_fn_t) (struct strbuf *sb,
+			       const char *placeholder,
+			       void *context);
+void strbuf_expand(struct strbuf *sb,
+		   const char *format,
+		   expand_fn_t fn,
+		   void *context);
 
 /**
  * Used as callback for `strbuf_expand()`, expects an array of
@@ -321,7 +327,9 @@ struct strbuf_expand_dict_entry {
 	const char *placeholder;
 	const char *value;
 };
-extern size_t strbuf_expand_dict_cb(struct strbuf *sb, const char *placeholder, void *context);
+size_t strbuf_expand_dict_cb(struct strbuf *sb,
+			     const char *placeholder,
+			     void *context);
 
 /**
  * Append the contents of one strbuf to another, quoting any
@@ -329,29 +337,29 @@ extern size_t strbuf_expand_dict_cb(struct strbuf *sb, const char *placeholder,
  * destination. This is useful for literal data to be fed to either
  * strbuf_expand or to the *printf family of functions.
  */
-extern void strbuf_addbuf_percentquote(struct strbuf *dst, const struct strbuf *src);
+void strbuf_addbuf_percentquote(struct strbuf *dst, const struct strbuf *src);
 
 /**
  * Append the given byte size as a human-readable string (i.e. 12.23 KiB,
  * 3.50 MiB).
  */
-extern void strbuf_humanise_bytes(struct strbuf *buf, off_t bytes);
+void strbuf_humanise_bytes(struct strbuf *buf, off_t bytes);
 
 /**
  * Add a formatted string to the buffer.
  */
 __attribute__((format (printf,2,3)))
-extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
+void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
 
 /**
  * Add a formatted string prepended by a comment character and a
  * blank to the buffer.
  */
 __attribute__((format (printf, 2, 3)))
-extern void strbuf_commented_addf(struct strbuf *sb, const char *fmt, ...);
+void strbuf_commented_addf(struct strbuf *sb, const char *fmt, ...);
 
 __attribute__((format (printf,2,0)))
-extern void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
+void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
 
 /**
  * Add the time specified by `tm`, as formatted by `strftime`.
@@ -361,9 +369,9 @@ extern void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
  * `suppress_tz_name`, when set, expands %Z internally to the empty
  * string rather than passing it to `strftime`.
  */
-extern void strbuf_addftime(struct strbuf *sb, const char *fmt,
-			    const struct tm *tm, int tz_offset,
-			    int suppress_tz_name);
+void strbuf_addftime(struct strbuf *sb, const char *fmt,
+		    const struct tm *tm, int tz_offset,
+		    int suppress_tz_name);
 
 /**
  * Read a given size of data from a FILE* pointer to the buffer.
@@ -373,14 +381,14 @@ extern void strbuf_addftime(struct strbuf *sb, const char *fmt,
  * `strbuf_read()`, `strbuf_read_file()` and `strbuf_getline_*()`
  * family of functions have the same behaviour as well.
  */
-extern size_t strbuf_fread(struct strbuf *, size_t, FILE *);
+size_t strbuf_fread(struct strbuf *sb, size_t size, FILE *file);
 
 /**
  * Read the contents of a given file descriptor. The third argument can be
  * used to give a hint about the file size, to avoid reallocs.  If read fails,
  * any partial read is undone.
  */
-extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
+ssize_t strbuf_read(struct strbuf *sb, int fd, size_t hint);
 
 /**
  * Read the contents of a given file descriptor partially by using only one
@@ -388,7 +396,7 @@ extern ssize_t strbuf_read(struct strbuf *, int fd, size_t hint);
  * file size, to avoid reallocs. Returns the number of new bytes appended to
  * the sb.
  */
-extern ssize_t strbuf_read_once(struct strbuf *, int fd, size_t hint);
+ssize_t strbuf_read_once(struct strbuf *sb, int fd, size_t hint);
 
 /**
  * Read the contents of a file, specified by its path. The third argument
@@ -396,19 +404,19 @@ extern ssize_t strbuf_read_once(struct strbuf *, int fd, size_t hint);
  * Return the number of bytes read or a negative value if some error
  * occurred while opening or reading the file.
  */
-extern ssize_t strbuf_read_file(struct strbuf *sb, const char *path, size_t hint);
+ssize_t strbuf_read_file(struct strbuf *sb, const char *path, size_t hint);
 
 /**
  * Read the target of a symbolic link, specified by its path.  The third
  * argument can be used to give a hint about the size, to avoid reallocs.
  */
-extern int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint);
+int strbuf_readlink(struct strbuf *sb, const char *path, size_t hint);
 
 /**
  * Write the whole content of the strbuf to the stream not stopping at
  * NUL bytes.
  */
-extern ssize_t strbuf_write(struct strbuf *sb, FILE *stream);
+ssize_t strbuf_write(struct strbuf *sb, FILE *stream);
 
 /**
  * Read a line from a FILE *, overwriting the existing contents of
@@ -422,10 +430,10 @@ extern ssize_t strbuf_write(struct strbuf *sb, FILE *stream);
 typedef int (*strbuf_getline_fn)(struct strbuf *, FILE *);
 
 /* Uses LF as the line terminator */
-extern int strbuf_getline_lf(struct strbuf *sb, FILE *fp);
+int strbuf_getline_lf(struct strbuf *sb, FILE *fp);
 
 /* Uses NUL as the line terminator */
-extern int strbuf_getline_nul(struct strbuf *sb, FILE *fp);
+int strbuf_getline_nul(struct strbuf *sb, FILE *fp);
 
 /*
  * Similar to strbuf_getline_lf(), but additionally treats a CR that
@@ -434,14 +442,14 @@ extern int strbuf_getline_nul(struct strbuf *sb, FILE *fp);
  * that can come from platforms whose native text format is CRLF
  * terminated.
  */
-extern int strbuf_getline(struct strbuf *, FILE *);
+int strbuf_getline(struct strbuf *sb, FILE *file);
 
 
 /**
  * Like `strbuf_getline`, but keeps the trailing terminator (if
  * any) in the buffer.
  */
-extern int strbuf_getwholeline(struct strbuf *, FILE *, int);
+int strbuf_getwholeline(struct strbuf *sb, FILE *file, int term);
 
 /**
  * Like `strbuf_getwholeline`, but operates on a file descriptor.
@@ -449,19 +457,19 @@ extern int strbuf_getwholeline(struct strbuf *, FILE *, int);
  * use it unless you need the correct position in the file
  * descriptor.
  */
-extern int strbuf_getwholeline_fd(struct strbuf *, int, int);
+int strbuf_getwholeline_fd(struct strbuf *sb, int fd, int term);
 
 /**
  * Set the buffer to the path of the current working directory.
  */
-extern int strbuf_getcwd(struct strbuf *sb);
+int strbuf_getcwd(struct strbuf *sb);
 
 /**
  * Add a path to a buffer, converting a relative path to an
  * absolute one in the process.  Symbolic links are not
  * resolved.
  */
-extern void strbuf_add_absolute_path(struct strbuf *sb, const char *path);
+void strbuf_add_absolute_path(struct strbuf *sb, const char *path);
 
 /**
  * Canonize `path` (make it absolute, resolve symlinks, remove extra
@@ -475,7 +483,7 @@ extern void strbuf_add_absolute_path(struct strbuf *sb, const char *path);
  * Callers that don't mind links should use the more lightweight
  * strbuf_add_absolute_path() instead.
  */
-extern void strbuf_add_real_path(struct strbuf *sb, const char *path);
+void strbuf_add_real_path(struct strbuf *sb, const char *path);
 
 
 /**
@@ -483,13 +491,13 @@ extern void strbuf_add_real_path(struct strbuf *sb, const char *path);
  * normalize_path_copy() for details. If an error occurs, the contents of "sb"
  * are left untouched, and -1 is returned.
  */
-extern int strbuf_normalize_path(struct strbuf *sb);
+int strbuf_normalize_path(struct strbuf *sb);
 
 /**
  * Strip whitespace from a buffer. The second parameter controls if
  * comments are considered contents to be removed or not.
  */
-extern void strbuf_stripspace(struct strbuf *buf, int skip_comments);
+void strbuf_stripspace(struct strbuf *buf, int skip_comments);
 
 static inline int strbuf_strip_suffix(struct strbuf *sb, const char *suffix)
 {
@@ -518,8 +526,8 @@ static inline int strbuf_strip_suffix(struct strbuf *sb, const char *suffix)
  * For lighter-weight alternatives, see string_list_split() and
  * string_list_split_in_place().
  */
-extern struct strbuf **strbuf_split_buf(const char *, size_t,
-					int terminator, int max);
+struct strbuf **strbuf_split_buf(const char *str, size_t len,
+				 int terminator, int max);
 
 static inline struct strbuf **strbuf_split_str(const char *str,
 					       int terminator, int max)
@@ -528,7 +536,7 @@ static inline struct strbuf **strbuf_split_str(const char *str,
 }
 
 static inline struct strbuf **strbuf_split_max(const struct strbuf *sb,
-						int terminator, int max)
+					       int terminator, int max)
 {
 	return strbuf_split_buf(sb->buf, sb->len, terminator, max);
 }
@@ -549,23 +557,23 @@ static inline struct strbuf **strbuf_split(const struct strbuf *sb,
  *   'element1, element2, ..., elementN'
  * to str.  If only one element, just write "element1" to str.
  */
-extern void strbuf_add_separated_string_list(struct strbuf *str,
-					     const char *sep,
-					     struct string_list *slist);
+void strbuf_add_separated_string_list(struct strbuf *str,
+				      const char *sep,
+				      struct string_list *slist);
 
 /**
  * Free a NULL-terminated list of strbufs (for example, the return
  * values of the strbuf_split*() functions).
  */
-extern void strbuf_list_free(struct strbuf **);
+void strbuf_list_free(struct strbuf **list);
 
 /**
  * Add the abbreviation, as generated by find_unique_abbrev, of `sha1` to
  * the strbuf `sb`.
  */
-extern void strbuf_add_unique_abbrev(struct strbuf *sb,
-				     const struct object_id *oid,
-				     int abbrev_len);
+void strbuf_add_unique_abbrev(struct strbuf *sb,
+			      const struct object_id *oid,
+			      int abbrev_len);
 
 /**
  * Launch the user preferred editor to edit a file and fill the buffer
@@ -574,15 +582,21 @@ extern void strbuf_add_unique_abbrev(struct strbuf *sb,
  * run in. If the buffer is NULL the editor is launched as usual but the
  * file's contents are not read into the buffer upon completion.
  */
-extern int launch_editor(const char *path, struct strbuf *buffer, const char *const *env);
+int launch_editor(const char *path,
+		  struct strbuf *buffer,
+		  const char *const *env);
 
-extern void strbuf_add_lines(struct strbuf *sb, const char *prefix, const char *buf, size_t size);
+void strbuf_add_lines(struct strbuf *sb,
+		      const char *prefix,
+		      const char *buf,
+		      size_t size);
 
 /**
  * Append s to sb, with the characters '<', '>', '&' and '"' converted
  * into XML entities.
  */
-extern void strbuf_addstr_xml_quoted(struct strbuf *sb, const char *s);
+void strbuf_addstr_xml_quoted(struct strbuf *sb,
+			      const char *s);
 
 /**
  * "Complete" the contents of `sb` by ensuring that either it ends with the
@@ -612,8 +626,8 @@ static inline void strbuf_complete_line(struct strbuf *sb)
  * If "allowed" is non-zero, restrict the set of allowed expansions. See
  * interpret_branch_name() for details.
  */
-extern void strbuf_branchname(struct strbuf *sb, const char *name,
-			      unsigned allowed);
+void strbuf_branchname(struct strbuf *sb, const char *name,
+		       unsigned allowed);
 
 /*
  * Like strbuf_branchname() above, but confirm that the result is
@@ -621,15 +635,15 @@ extern void strbuf_branchname(struct strbuf *sb, const char *name,
  *
  * The return value is "0" if the result is valid, and "-1" otherwise.
  */
-extern int strbuf_check_branch_ref(struct strbuf *sb, const char *name);
+int strbuf_check_branch_ref(struct strbuf *sb, const char *name);
 
-extern void strbuf_addstr_urlencode(struct strbuf *, const char *,
-				    int reserved);
+void strbuf_addstr_urlencode(struct strbuf *sb, const char *name,
+			     int reserved);
 
 __attribute__((format (printf,1,2)))
-extern int printf_ln(const char *fmt, ...);
+int printf_ln(const char *fmt, ...);
 __attribute__((format (printf,2,3)))
-extern int fprintf_ln(FILE *fp, const char *fmt, ...);
+int fprintf_ln(FILE *fp, const char *fmt, ...);
 
 char *xstrdup_tolower(const char *);
 char *xstrdup_toupper(const char *);