fix wrong link in user and organization profile when using relative url (#28617)

fix #28436.
the doc https://docs.gitea.com/usage/profile-readme maybe also need to
be updated to tell that
the main branch is necessary,which means the following three conditions
should be satisfied:
- repo: **.profile**
- branch: **[default branch]**
- markdown: **README.md**

routers/web/org/home.go

@@ -18,6 +18,7 @@ import (
 	"code.gitea.io/gitea/modules/markup"
 	"code.gitea.io/gitea/modules/markup/markdown"
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/util"
 	shared_user "code.gitea.io/gitea/routers/web/shared/user"
 )
 
@@ -157,14 +158,14 @@ func Home(ctx *context.Context) {
 
 	ctx.Data["ShowMemberAndTeamTab"] = ctx.Org.IsMember || len(members) > 0
 
-	profileGitRepo, profileReadmeBlob, profileClose := shared_user.FindUserProfileReadme(ctx, ctx.Doer)
+	profileDbRepo, profileGitRepo, profileReadmeBlob, profileClose := shared_user.FindUserProfileReadme(ctx, ctx.Doer)
 	defer profileClose()
-	prepareOrgProfileReadme(ctx, profileGitRepo, profileReadmeBlob)
+	prepareOrgProfileReadme(ctx, profileGitRepo, profileDbRepo, profileReadmeBlob)
 
 	ctx.HTML(http.StatusOK, tplOrgHome)
 }
 
-func prepareOrgProfileReadme(ctx *context.Context, profileGitRepo *git.Repository, profileReadme *git.Blob) {
+func prepareOrgProfileReadme(ctx *context.Context, profileGitRepo *git.Repository, profileDbRepo *repo_model.Repository, profileReadme *git.Blob) {
 	if profileGitRepo == nil || profileReadme == nil {
 		return
 	}
@@ -172,10 +173,14 @@ func prepareOrgProfileReadme(ctx *context.Context, profileGitRepo *git.Repositor
 	if bytes, err := profileReadme.GetBlobContent(setting.UI.MaxDisplayFileSize); err != nil {
 		log.Error("failed to GetBlobContent: %v", err)
 	} else {
+		// Pass URLPrefix to markdown render for the full link of media elements.
+		// The profile of default branch would be shown.
+		prefix := profileDbRepo.Link() + "/src/branch/" + util.PathEscapeSegments(profileDbRepo.DefaultBranch)
 		if profileContent, err := markdown.RenderString(&markup.RenderContext{
-			Ctx:     ctx,
-			GitRepo: profileGitRepo,
-			Metas:   map[string]string{"mode": "document"},
+			Ctx:       ctx,
+			GitRepo:   profileGitRepo,
+			URLPrefix: prefix,
+			Metas:     map[string]string{"mode": "document"},
 		}, bytes); err != nil {
 			log.Error("failed to RenderString: %v", err)
 		} else {

routers/web/shared/user/header.go

@@ -87,7 +87,7 @@ func PrepareContextForProfileBigAvatar(ctx *context.Context) {
 	}
 }
 
-func FindUserProfileReadme(ctx *context.Context, doer *user_model.User) (profileGitRepo *git.Repository, profileReadmeBlob *git.Blob, profileClose func()) {
+func FindUserProfileReadme(ctx *context.Context, doer *user_model.User) (profileDbRepo *repo_model.Repository, profileGitRepo *git.Repository, profileReadmeBlob *git.Blob, profileClose func()) {
 	profileDbRepo, err := repo_model.GetRepositoryByName(ctx, ctx.ContextUser.ID, ".profile")
 	if err == nil {
 		perm, err := access_model.GetUserRepoPermission(ctx, profileDbRepo, doer)
@@ -105,7 +105,7 @@ func FindUserProfileReadme(ctx *context.Context, doer *user_model.User) (profile
 	} else if !repo_model.IsErrRepoNotExist(err) {
 		log.Error("FindUserProfileReadme failed to GetRepositoryByName: %v", err)
 	}
-	return profileGitRepo, profileReadmeBlob, func() {
+	return profileDbRepo, profileGitRepo, profileReadmeBlob, func() {
 		if profileGitRepo != nil {
 			_ = profileGitRepo.Close()
 		}
@@ -115,7 +115,7 @@ func FindUserProfileReadme(ctx *context.Context, doer *user_model.User) (profile
 func RenderUserHeader(ctx *context.Context) {
 	prepareContextForCommonProfile(ctx)
 
-	_, profileReadmeBlob, profileClose := FindUserProfileReadme(ctx, ctx.Doer)
+	_, _, profileReadmeBlob, profileClose := FindUserProfileReadme(ctx, ctx.Doer)
 	defer profileClose()
 	ctx.Data["HasProfileReadme"] = profileReadmeBlob != nil
 }

routers/web/user/profile.go

@@ -64,17 +64,17 @@ func userProfile(ctx *context.Context) {
 		ctx.Data["HeatmapTotalContributions"] = activities_model.GetTotalContributionsInHeatmap(data)
 	}
 
-	profileGitRepo, profileReadmeBlob, profileClose := shared_user.FindUserProfileReadme(ctx, ctx.Doer)
+	profileDbRepo, profileGitRepo, profileReadmeBlob, profileClose := shared_user.FindUserProfileReadme(ctx, ctx.Doer)
 	defer profileClose()
 
 	showPrivate := ctx.IsSigned && (ctx.Doer.IsAdmin || ctx.Doer.ID == ctx.ContextUser.ID)
-	prepareUserProfileTabData(ctx, showPrivate, profileGitRepo, profileReadmeBlob)
+	prepareUserProfileTabData(ctx, showPrivate, profileDbRepo, profileGitRepo, profileReadmeBlob)
 	// call PrepareContextForProfileBigAvatar later to avoid re-querying the NumFollowers & NumFollowing
 	shared_user.PrepareContextForProfileBigAvatar(ctx)
 	ctx.HTML(http.StatusOK, tplProfile)
 }
 
-func prepareUserProfileTabData(ctx *context.Context, showPrivate bool, profileGitRepo *git.Repository, profileReadme *git.Blob) {
+func prepareUserProfileTabData(ctx *context.Context, showPrivate bool, profileDbRepo *repo_model.Repository, profileGitRepo *git.Repository, profileReadme *git.Blob) {
 	// if there is a profile readme, default to "overview" page, otherwise, default to "repositories" page
 	// if there is not a profile readme, the overview tab should be treated as the repositories tab
 	tab := ctx.FormString("tab")
@@ -233,10 +233,18 @@ func prepareUserProfileTabData(ctx *context.Context, showPrivate bool, profileGi
 		if bytes, err := profileReadme.GetBlobContent(setting.UI.MaxDisplayFileSize); err != nil {
 			log.Error("failed to GetBlobContent: %v", err)
 		} else {
+			// Give the URLPrefix to the markdown render for the full link of media element.
+			// the media link usually be like /[user]/[repoName]/media/branch/[branchName],
+			// 	Eg. /Tom/.profile/media/branch/main
+			// The branch shown on the profile page is the default branch, this need to be in sync with doc, see:
+			//	https://docs.gitea.com/usage/profile-readme
+
+			prefix := profileDbRepo.Link() + "/src/branch/" + util.PathEscapeSegments(profileDbRepo.DefaultBranch)
 			if profileContent, err := markdown.RenderString(&markup.RenderContext{
-				Ctx:     ctx,
-				GitRepo: profileGitRepo,
-				Metas:   map[string]string{"mode": "document"},
+				Ctx:       ctx,
+				GitRepo:   profileGitRepo,
+				URLPrefix: prefix,
+				Metas:     map[string]string{"mode": "document"},
 			}, bytes); err != nil {
 				log.Error("failed to RenderString: %v", err)
 			} else {